CmdGetAuthInfo: Don't use non-git jw-build

Don't try to use non-git jw-build repositories to retrieve auth info.

Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/build/cmds/CmdGetAuthInfo.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 
-import re
+import re, os
 from argparse import Namespace, ArgumentParser
 from urllib.parse import urlparse
 
@@ -19,7 +19,11 @@ class CmdGetAuthInfo(Cmd): # export
         parser.add_argument('--password', help='Show password', action='store_true', default=False)
 
     def _run(self, args: Namespace) -> None:
-        remotes = run_cmd(['git', '-C', self.app.proj_dir('jw-build'), 'remote', '-v'])
+        jw_build_dir = self.app.proj_dir('jw-build')
+        if not os.path.isdir(jw_build_dir + '/.git'):
+            self.app.debug(f'jw-build directory is not a Git repo: {jw_build_dir}')
+            return
+        remotes = run_cmd(['git', '-C', jw_build_dir, 'remote', '-v'])
         result: dict[str, str] = {}
         keys = ['username', 'password']
         for line in remotes.split('\n'):