Properly handle failed git commands when redirect_stderr=True (#33203)

* Properly handle redirected stderr

When running subprocess.Popen.communicate() on a command run with stderr
redirected to subprocess.STDOUT, the 2nd element of the return tuple
(representing the stderr) will be None, since all of the standard error
was sent to stdout.

Functions interpreting the return data from cmd.run_all will be
expecting the ``stderr`` key in the return dict to contain a string, not
a NoneType, so this commit forces the stderr to be set to an empty
string when redirect_stderr is True.

* Look at stdout instead of stderr for error text when redirect_stderr is True

salt/modules/cmdmod.py

@@ -449,6 +449,10 @@ def _run(cmd,
             return ret
 
         out, err = proc.stdout, proc.stderr
+        if err is None:
+            # Will happen if redirect_stderr is True, since stderr was sent to
+            # stdout.
+            err = ''
 
         if rstrip:
             if out is not None:

salt/modules/git.py

@@ -238,9 +238,9 @@ def _git_run(command, cwd=None, runas=None, identity=None,
             if result['retcode'] == 0:
                 return result
             else:
-                stderr = \
-                    salt.utils.url.redact_http_basic_auth(result['stderr'])
-                errors.append(stderr)
+                err = result['stdout' if redirect_stderr else 'stderr']
+                if err:
+                    errors.append(salt.utils.url.redact_http_basic_auth(err))
 
         # We've tried all IDs and still haven't passed, so error out
         if failhard:
@@ -281,9 +281,10 @@ def _git_run(command, cwd=None, runas=None, identity=None,
                 msg = 'Command \'{0}\' failed'.format(
                     salt.utils.url.redact_http_basic_auth(gitcommand)
                 )
-                if result['stderr']:
+                err = result['stdout' if redirect_stderr else 'stderr']
+                if err:
                     msg += ': {0}'.format(
-                        salt.utils.url.redact_http_basic_auth(result['stderr'])
+                        salt.utils.url.redact_http_basic_auth(err)
                     )
                 raise CommandExecutionError(msg)
             return result