gin-cli does not write to stderr when a checkout fails

This occurred during my testing of the GinUI client:
When a checkout fails for whatever reason (in this particular case presumably due to a timeout somewhere), gin-cli does not write anything to stderr. GinUI requires that, on failure, _something_ is written to stderr (preferably something meaningful) to figure out whether or not gin-cli worked correctly.

Relevant portions of the gin-cli log:
```
2018/03/03 12:18:36 COMMAND: get --json achilleas/gin-ui-installers
2018/03/03 12:18:36 Reading config file C:\Users\fwolt\AppData\Roaming\g-node\gin\config.yml
2018/03/03 12:18:36 Configuration values
2018/03/03 12:18:36 {GinHost:https://web.gin.g-node.org:443 GitHost:gin.g-node.org:22 GitUser:git GitHostKey:gin.g-node.org,141.84.41.216 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBE5IBgKP3nUryEFaACwY4N3jlqDx8Qw1xAxU2Xpt5V0p9RNefNnedVmnIBV6lA3n+9kT1OSbyqA/+SgsQ57nHo0= Bin:{Git:git GitAnnex:git-annex SSH:ssh} Annex:{Exclude:[] MinSize:10M}}
2018/03/03 12:18:36 Token read OK
2018/03/03 12:18:36 env GIT_SSH_COMMAND=ssh -i C:/Users/fwolt/AppData/Roaming/g-node/gin/FWoltermann.key -o IdentitiesOnly=yes -o StrictHostKeyChecking=yes -o UserKnownHostsFile=C:/Users/fwolt/AppData/Roaming/g-node/gin/ginhostkey
2018/03/03 12:18:36 Running shell command (Dir: .): git-annex version --raw
2018/03/03 12:18:36 Token read OK
2018/03/03 12:18:36 CloneRepo
2018/03/03 12:18:36 Token read OK
2018/03/03 12:18:36 env GIT_SSH_COMMAND=ssh -i C:/Users/fwolt/AppData/Roaming/g-node/gin/FWoltermann.key -o IdentitiesOnly=yes -o StrictHostKeyChecking=yes -o UserKnownHostsFile=C:/Users/fwolt/AppData/Roaming/g-node/gin/ginhostkey
2018/03/03 12:18:36 Running shell command (Dir: .): git -c core.symlinks=false clone --progress ssh://git@gin.g-node.org:22/achilleas/gin-ui-installers
2018/03/03 12:20:45 Error during clone command
2018/03/03 12:20:45 [stdout]
2018/03/03 12:20:45 [stderr]
Cloning into 'gin-ui-installers'...
remote: Counting objects: 1483, done.
remote: Compressing objects: 0% (1/1127)
remote: Compressing objects: 1% (12/1127)
remote: Compressing objects: 2% (23/1127)
remote: Compressing objects: 3% (34/1127)
remote: Compressing objects: 4% (46/1127)
remote: Compressing objects: 5% (57/1127)
remote: Compressing objects: 6% (68/1127)
remote: Compressing objects: 7% (79/1127)
remote: Compressing objects: 8% (91/1127)
remote: Compressing objects: 9% (102/1127)
remote: Compressing objects: 10% (113/1127)
remote: Compressing objects: 11% (124/1127)
remote: Compressing objects: 12% (136/1127)
remote: Compressing objects: 13% (147/1127)
remote: Compressing objects: 14% (158/1127)
remote: Compressing objects: 15% (170/1127)
remote: Compressing objects: 16% (181/1127)
remote: Compressing objects: 17% (192/1127)
remote: Compressing objects: 18% (203/1127)
remote: Compressing objects: 19% (215/1127)
remote: Compressing objects: 20% (226/1127)
remote: Compressing objects: 21% (237/1127)
remote: Compressing objects: 22% (248/1127)
remote: Compressing objects: 23% (260/1127)
remote: Compressing objects: 24% (271/1127)
remote: Compressing objects: 25% (282/1127)
remote: Compressing objects: 26% (294/1127)
remote: Compressing objects: 27% (305/1127)
remote: Compressing objects: 28% (316/1127)
remote: Compressing objects: 29% (327/1127)
remote: Compressing objects: 30% (339/1127)
remote: Compressing objects: 31% (350/1127)
remote: Compressing objects: 32% (361/1127)
remote: Compressing objects: 33% (372/1127)
remote: Compressing objects: 34% (384/1127)
remote: Compressing objects: 35% (395/1127)
remote: Compressing objects: 36% (406/1127)
remote: Compressing objects: 37% (417/1127)
remote: Compressing objects: 38% (429/1127)
remote: Compressing objects: 39% (440/1127)
remote: Compressing objects: 40% (451/1127)
remote: Compressing objects: 41% (463/1127)
remote: Compressing objects: 42% (474/1127)
remote: Compressing objects: 43% (485/1127)
remote: Compressing objects: 44% (496/1127)
remote: Compressing objects: 45% (508/1127)
remote: Compressing objects: 46% (519/1127)
remote: Compressing objects: 47% (530/1127)
remote: Compressing objects: 48% (541/1127)
remote: Compressing objects: 49% (553/1127)
remote: Compressing objects: 50% (564/1127)
remote: Compressing objects: 51% (575/1127)
remote: Compressing objects: 52% (587/1127)
remote: Compressing objects: 53% (598/1127)
remote: Compressing objects: 54% (609/1127)
remote: Compressing objects: 55% (620/1127)
remote: Compressing objects: 56% (632/1127)
remote: Compressing objects: 57% (643/1127)
remote: Compressing objects: 58% (654/1127)
remote: Compressing objects: 59% (665/1127)
remote: Compressing objects: 60% (677/1127)
remote: Compressing objects: 61% (688/1127)
remote: Compressing objects: 62% (699/1127)
remote: Compressing objects: 63% (711/1127)
remote: Compressing objects: 64% (722/1127)
remote: Compressing objects: 65% (733/1127)
remote: Compressing objects: 66% (744/1127)
remote: Compressing objects: 67% (756/1127)
remote: Compressing objects: 68% (767/1127)
remote: Compressing objects: 69% (778/1127)
remote: Compressing objects: 70% (789/1127)
remote: Compressing objects: 71% (801/1127)
remote: Compressing objects: 72% (812/1127)
remote: Compressing objects: 73% (823/1127)
remote: Compressing objects: 74% (834/1127)
remote: Compressing objects: 75% (846/1127)
remote: Compressing objects: 76% (857/1127)
remote: Compressing objects: 77% (868/1127)
remote: Compressing objects: 78% (880/1127)
remote: Compressing objects: 79% (891/1127)
remote: Compressing objects: 80% (902/1127)
remote: Compressing objects: 81% (913/1127)
remote: Compressing objects: 82% (925/1127)
remote: Compressing objects: 83% (936/1127)
remote: Compressing objects: 84% (947/1127)
remote: Compressing objects: 85% (958/1127)
remote: Compressing objects: 86% (970/1127)
remote: Compressing objects: 87% (981/1127)
remote: Compressing objects: 88% (992/1127)
remote: Compressing objects: 89% (1004/1127)
remote: Compressing objects: 90% (1015/1127)
remote: Compressing objects: 91% (1026/1127)
remote: Compressing objects: 92% (1037/1127)
remote: Compressing objects: 93% (1049/1127)
remote: Compressing objects: 94% (1060/1127)
remote: Compressing objects: 95% (1071/1127)
remote: Compressing objects: 96% (1082/1127)
remote: Compressing objects: 97% (1094/1127)
remote: Compressing objects: 98% (1105/1127)
remote: Compressing objects: 99% (1116/1127)
remote: Compressing objects: 100% (1127/1127)
remote: Compressing objects: 100% (1127/1127), done.
Receiving objects: 0% (1/1483)
Receiving objects: 1% (15/1483)
Receiving objects: 2% (30/1483)
Receiving objects: 3% (45/1483)
Receiving objects: 4% (60/1483)
Receiving objects: 5% (75/1483)
Receiving objects: 6% (89/1483)
Receiving objects: 7% (104/1483)
Receiving objects: 8% (119/1483)
Receiving objects: 9% (134/1483)
Receiving objects: 10% (149/1483)
Receiving objects: 11% (164/1483)
Receiving objects: 12% (178/1483)
Receiving objects: 13% (193/1483)
Receiving objects: 14% (208/1483)
Receiving objects: 15% (223/1483)
Receiving objects: 16% (238/1483)
Receiving objects: 17% (253/1483)
Receiving objects: 18% (267/1483)
Receiving objects: 19% (282/1483)
Receiving objects: 20% (297/1483)
Receiving objects: 21% (312/1483)
Receiving objects: 22% (327/1483)
Receiving objects: 23% (342/1483)
Receiving objects: 24% (356/1483)
Receiving objects: 25% (371/1483)
Receiving objects: 26% (386/1483)
Receiving objects: 27% (401/1483)
Receiving objects: 28% (416/1483)
Receiving objects: 29% (431/1483)
Receiving objects: 30% (445/1483)
Receiving objects: 31% (460/1483)
Receiving objects: 32% (475/1483)
Receiving objects: 33% (490/1483)
Receiving objects: 34% (505/1483)
Receiving objects: 35% (520/1483)
Receiving objects: 36% (534/1483)
Receiving objects: 37% (549/1483)
Receiving objects: 38% (564/1483)
Receiving objects: 39% (579/1483)
Receiving objects: 40% (594/1483)
Receiving objects: 41% (609/1483)
Receiving objects: 42% (623/1483)
Receiving objects: 43% (638/1483)
Receiving objects: 44% (653/1483)
Receiving objects: 45% (668/1483)
Receiving objects: 46% (683/1483)
Receiving objects: 47% (698/1483)
Receiving objects: 48% (712/1483)
Receiving objects: 49% (727/1483)
Receiving objects: 50% (742/1483)
Receiving objects: 51% (757/1483)
Receiving objects: 52% (772/1483)
Receiving objects: 53% (786/1483)
Receiving objects: 54% (801/1483)
Receiving objects: 55% (816/1483)
Receiving objects: 56% (831/1483)
Receiving objects: 57% (846/1483)
Receiving objects: 58% (861/1483)
Receiving objects: 59% (875/1483)
Receiving objects: 60% (890/1483)
Receiving objects: 61% (905/1483)
Receiving objects: 62% (920/1483)
Receiving objects: 63% (935/1483)
Receiving objects: 64% (950/1483)
Receiving objects: 65% (964/1483)
Receiving objects: 66% (979/1483)
Receiving objects: 67% (994/1483)
Receiving objects: 68% (1009/1483)
Receiving objects: 69% (1024/1483)
Receiving objects: 70% (1039/1483)
Receiving objects: 71% (1053/1483)
Receiving objects: 72% (1068/1483)
Receiving objects: 73% (1083/1483)
Receiving objects: 74% (1098/1483)
Receiving objects: 75% (1113/1483)
Receiving objects: 76% (1128/1483)
Receiving objects: 77% (1142/1483)
Receiving objects: 78% (1157/1483)
Receiving objects: 79% (1172/1483)
Receiving objects: 79% (1184/1483), 268.00 KiB | 239.00 KiB/s
Receiving objects: 79% (1184/1483), 636.00 KiB | 287.00 KiB/s
Receiving objects: 79% (1184/1483), 1.06 MiB | 336.00 KiB/s
Receiving objects: 79% (1184/1483), 1.56 MiB | 369.00 KiB/s
Receiving objects: 79% (1184/1483), 2.06 MiB | 409.00 KiB/s
Receiving objects: 79% (1184/1483), 2.59 MiB | 460.00 KiB/s
Receiving objects: 79% (1184/1483), 3.15 MiB | 492.00 KiB/s
Receiving objects: 79% (1184/1483), 3.28 MiB | 468.00 KiB/s
Receiving objects: 79% (1184/1483), 3.87 MiB | 491.00 KiB/s
Receiving objects: 79% (1184/1483), 4.43 MiB | 509.00 KiB/s
Receiving objects: 79% (1184/1483), 4.93 MiB | 501.00 KiB/s
Receiving objects: 79% (1184/1483), 5.50 MiB | 503.00 KiB/s
Receiving objects: 79% (1184/1483), 6.00 MiB | 517.00 KiB/s
Connection reset by 141.84.41.216 port 22
fatal: early EOF
fatal: The remote end hung up unexpectedly
fatal: index-pack failed
2018/03/03 12:20:45 LOGINIT
2018/03/03 12:20:45 COMMAND: ls --json
2018/03/03 12:20:45 Reading config file C:\Users\fwolt\AppData\Roaming\g-node\gin\config.yml
2018/03/03 12:20:45 Configuration values
2018/03/03 12:20:45 {GinHost:https://web.gin.g-node.org:443 GitHost:gin.g-node.org:22 GitUser:git GitHostKey:gin.g-node.org,141.84.41.216 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBE5IBgKP3nUryEFaACwY4N3jlqDx8Qw1xAxU2Xpt5V0p9RNefNnedVmnIBV6lA3n+9kT1OSbyqA/+SgsQ57nHo0= Bin:{Git:git GitAnnex:git-annex SSH:ssh} Annex:{Exclude:[] MinSize:10M}}
2018/03/03 12:20:45 Token read OK
2018/03/03 12:20:45 env GIT_SSH_COMMAND=ssh -i C:/Users/fwolt/AppData/Roaming/g-node/gin/FWoltermann.key -o IdentitiesOnly=yes -o StrictHostKeyChecking=yes -o UserKnownHostsFile=C:/Users/fwolt/AppData/Roaming/g-node/gin/ginhostkey
2018/03/03 12:20:45 Running shell command (Dir: .): git-annex version --raw
2018/03/03 12:20:46 IsRepo '.'?
2018/03/03 12:20:46 false

```