Print warning when updated tag doesn't exist?

[nusbaume]

When you set fxtag to a non-existent tag, git-fleximod just silently grabs the original submodule hash/tag. While I think this behavior is fine, it would be nice to print a warning to the screen that the new tag wasn't found, so that the user/developer is aware that their .gitmodules change was not correct.

To reproduce the issue:

1. Grab a codebase (e.g. ESCOMP/CESM) that uses git-fleximod.
2. Update the .gitmodules file so that one of the submodules has an fxtag entry that is completely made up or non-existent.
3. Run bin/git-fleximod update, and note that it will simply ignore the bad fxtag setting and grab the original submodule tag/hash, without any sort of notification.

This was tested with the latest version of git-fleximod (v1.0.1).

[jedwards4b]

I just tried this and got what I think is a perfectly clear message - please provide instructions to reproduce:

diff --git a/.gitmodules b/.gitmodules
index ec9fe01..e5fec2f 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -37,7 +37,7 @@
         path = cime
         url = https://github.com/ESMCI/cime
         fxDONOTUSEurl = https://github.com/ESMCI/cime
-       fxtag = cime6.1.113
+       fxtag = cime6.1.113fred
         fxrequired = ToplevelRequired

 git fleximod update cime
Cmd('git') failed due to: exit code(128)
  cmdline: git fetch origin refs/tags/cime6.1.113fred:refs/tags/cime6.1.113fred
  stderr: 'fatal: couldn't find remote ref refs/tags/cime6.1.113fred'