fix: pass user/email via env also for "preset"-auth

GitHelper's "preset"-auth-mode instructs GitHelper to assume underlying
git-repository is already configured w.r.t. authentication. However,
also for local operations (e.g. create a commit or note), git will
require username and email-address. Hence, let GitHelper also pass those
(if configured) for preset-case.

Author: ccwienk

gitutil.py

@@ -149,7 +149,18 @@ def _authenticated_remote(self):
                 git_cfg=self.git_cfg,
             )
         elif auth_type is AuthType.PRESET:
-            yield os.environ, self.repo.remotes[0]
+            cmd_env = os.environ.copy()
+            if (user := self.git_cfg.user_name):
+                if not 'GIT_AUTHOR_NAME' in cmd_env:
+                    cmd_env['GIT_AUTHOR_NAME'] = user
+                if not 'GIT_COMMITTER_NAME' in cmd_env:
+                    cmd_env['GIT_COMMITTER_NAME'] = user
+            if (email := self.git_cfg.user_email):
+                if not 'GIT_AUTHOR_EMAIL' in cmd_env:
+                    cmd_env['GIT_AUTHOR_EMAIL'] = email
+                if not 'GIT_COMMITTER_EMAIL' in cmd_env:
+                    cmd_env['GIT_COMMITTER_EMAIL'] = email
+            yield cmd_env, self.repo.remotes[0]
             return
         else:
             raise NotImplementedError