Samsung Galaxy S5 no PARTNAME warning

This is an amazing tool - thank you so much for taking the time to write it!

That having been said, it asked me very politely to raise an issue while I was experimenting with it, so I am.

I'm backing up a Samsung Galaxy S5, running Cyanogenmod 13 and TWRP recovery. The output from tetherback is:

```
tetherback v0.9.1
Found ADB version 1.0.36
Using default transfer method: adb exec-out pipe (--exec-out)
Device reports kernel 3.4.0-twrp-klte-unified-1.7
Device reports TWRP version 3.1.0-0
Reading partition map for mmcblk0 (26 partitions)...
partition map: 100%
Reading partition map for mmcblk0rpmb (0 partitions)...
partition map: 100%
Reading partition map for mmcblk1 (1 partitions)...
partition map: N/A% WARNING: partition mmcblk1p1 has no PARTNAME in its uevent file
Please report this issue at https://github.com/dlenski/tetherback/issues
Please post the entire output from tetherback!
partition map: 100%
Saving backup images in ./twrp-backup-2017-07-07--22-44-53/ ...
Saving partition boot (mmcblk0p15), 13 MiB uncompressed...
boot.emmc.win: 100% 5.7 MiB/s 9.3 MiB
Saving tarball of mmcblk0p23 (mounted at /system), 2500 MiB uncompressed...
system.ext4.win: 100% 5.7 MiB/s 389.1 MiB
Saving tarball of mmcblk0p26 (mounted at /data), 12132 MiB uncompressed...
data.ext4.win: 100% 6.0 MiB/s 8.5 GiB
Backup complete.
```