Template mechanism has trouble switching branches

[aivanova5]

Problem description

Setting the template config is inconsistent and gets tripped up when switching branches back n forth.

Steps to reproduce

aivanovalocal@PC99458 tariff_design % gridlabd template config set GITBRANCH "master"
aivanovalocal@PC99458 tariff_design % gridlabd template config set GITBRANCH "add-tariff-design"
aivanovalocal@PC99458 tariff_design % gridlabd template config                                  
ERROR 2: commit is not valid
ERROR 1: <class 'SystemExit'> 2
ERROR [gridlabd-template]: Branch not found
GITHUB="https://github.com/"
GITHUBUSERCONTENT="https://raw.githubusercontent.com/"
ORGANIZATION="US/CA/SLAC"
GITUSER="hipas"
GITREPO="gridlabd-template"
GITBRANCH="add-tariff-design"
CACHEDIR="/usr/local/opt/gridlabd/4.3.1-220922-develop/share/gridlabd/template/US/CA/SLAC/.gridlabd-template"
DATADIR="/usr/local/opt/gridlabd/4.3.1-220922-develop/share/gridlabd/template/US/CA/SLAC"
aivanovalocal@PC99458 tariff_design % gridlabd template config set GITBRANCH "master"           
ERROR 2: commit is not valid
ERROR 1: <class 'SystemExit'> 2
ERROR [gridlabd-template]: Branch not found

Expected behavior

No errors when switching branches.

System information

• GridLAB-D version: HiPAS GridLAB-D 4.3.1-220922 (develop) Darwin
• Operating system: Darwin PC99458 21.6.0 Darwin Kernel Version 21.6.0: Wed Aug 10 14:25:27 PDT 2022; root:xnu-8020.141.5~2/RELEASE_X86_64 x86_64

[dchassin]

The problem is the repo doesn't contain the branch specified. This is a deeper issue with both the config set command and the attempt to use the config once it is set.

1. The config set should check whether the setting is acceptable/valid and explain why it is not.
2. The attempt to use the config doesn't diagnose the failure clearly. The error message is incredibly opaque and needs to be made more clear.