gsmap global sizes different

### Brief summary of bug

I am trying a hybrid run with a very recent CTSM release which now requires specifying the ocean resolution. Previously I had specified f09_f09, now I specify f09_f09_mg17. Additionally, I am using my own DATM files (that I have used in the past) and now have to specify DATM_MODE=CPLHIST (as opposed to CPLHISTForcing) and get the following error message:

11240: (seq_map_gsmapcheck)gsmap global sizes different 55296 13824
11240: ERROR: (seq_map_gsmapcheck) different gsmap size

### General bug information

The tag that worked was:
0[1875] cheyenne1:/<4>CESM/ctsm_june12_2018 > git describe
clm5.0.dev013

The release that is failing is:
0[2032] cheyenne5:/<3>CESM/ctsm > git describe
release-clm5.0.04

Tried again (and had a similar failure) with
1[1884] cheyenne1:/<3>CESM/ctsm > git status
HEAD detached at release-clm5.0.01
nothing to commit, working directory clean

**Does this bug cause significantly incorrect results in the model's science?** [Yes / No]

The model does not run.

**Configurations affected:** [Fill this in if known.]

2000_DATM%GSWP3v1_CLM50%BGC-CROP_SICE_SOCN_MOSART_SGLC_SWAV

### Details of bug

I am using my own DATM files - not sure if that is relevant.

### Important details of your setup / configuration so we can reproduce the bug

/glade/scratch/thoar/ctsm/clm5_f09_freerun80/run