Fix UnboundLocalError remote_head in git (#19057)

* Fix UnboundLocalError remote_head in git

Fixes #5505

The use of remote_head was a leftover of #4562.
remote_head is not necessary, since the repo is unchanged anyway and
after is set correctly.

Further changes:
* Set changed=True and msg once local_mods are detected and reset.
* Remove need_fetch that is always True (due to previous if) to improve
clarity
* Don't exit early for local_mods but run submodules update and
switch_version

* Add test for git with local modifications
(cherry picked from afca957)

source_control/git.py

@@ -871,7 +871,7 @@ def main():
     ssh_opts  = module.params['ssh_opts']
     umask  = module.params['umask']
 
-    result = dict( warnings=list() )
+    result = dict(changed = False, warnings=list())
 
     # evaluate and set the umask before doing anything else
     if umask is not None:
@@ -951,7 +951,7 @@ def main():
         # this does no checking that the repo is the actual repo
         # requested.
         result['before'] = get_version(module, git_path, dest)
-        result.update(changed=False, after=result['before'])
+        result.update(after=result['before'])
         module.exit_json(**result)
     else:
         # else do a pull
@@ -964,6 +964,7 @@ def main():
             # if force and in non-check mode, do a reset
             if not module.check_mode:
                 reset(git_path, module, dest)
+                result.update(changed=True, msg='Local modifications exist.')
 
         # exit if already at desired sha version
         if module.check_mode:
@@ -974,27 +975,20 @@ def main():
         if remote_url_changed:
             result.update(remote_url_changed=True)
 
-        if need_fetch:
-            if module.check_mode:
-                remote_head = get_remote_head(git_path, module, dest, version, remote, bare)
-                result.update(changed=(result['before'] != remote_head), after=remote_head)
-                # FIXME: This diff should fail since the new remote_head is not fetched yet?!
-                if module._diff:
-                    diff = get_diff(module, git_path, dest, repo, remote, depth, bare, result['before'], result['after'])
-                    if diff:
-                        result['diff'] = diff
-                module.exit_json(**result)
-            else:
-                fetch(git_path, module, repo, dest, version, remote, depth, bare, refspec, git_version_used)
+        if module.check_mode:
+            remote_head = get_remote_head(git_path, module, dest, version, remote, bare)
+            result.update(changed=(result['before'] != remote_head), after=remote_head)
+            # FIXME: This diff should fail since the new remote_head is not fetched yet?!
+            if module._diff:
+                diff = get_diff(module, git_path, dest, repo, remote, depth, bare, result['before'], result['after'])
+                if diff:
+                    result['diff'] = diff
+            module.exit_json(**result)
+        else:
+            fetch(git_path, module, repo, dest, version, remote, depth, bare, refspec, git_version_used)
 
         result['after'] = get_version(module, git_path, dest)
 
-        if result['before'] == result['after']:
-            if local_mods:
-                result.update(changed=True, after=remote_head, msg='Local modifications exist')
-                # no diff, since the repo didn't change
-                module.exit_json(**result)
-
     # switch to version specified regardless of whether
     # we got new revisions from the repository
     if not bare:
@@ -1017,7 +1011,6 @@ def main():
     # determine if we changed anything
     result['after'] = get_version(module, git_path, dest)
 
-    result.update(changed=False)
     if result['before'] != result['after'] or local_mods or submodules_updated or remote_url_changed:
         result.update(changed=True)
         if module._diff: