git_config: update error handling with no config file

Now that _do throws an exception when `git` fails, update the logic
that tries to read config files but the file doesn't exist.

Bug: b/192664812
Change-Id: I6417ecd70891b8f2d5f2bdb819f91df69ac4b70c
Test: `repo upload` no longer crashes when .repo/config doesn't exist
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/319295
Reviewed-by: Jack Neus <jackneus@google.com>
Tested-by: Mike Frysinger <vapier@google.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/git_config.py b/git_config.py
index bc70d160..3cd09391 100644
--- a/git_config.py
+++ b/git_config.py
@@ -371,9 +371,10 @@ class GitConfig(object):
 
     """
     c = {}
-    d = self._do('--null', '--list')
-    if d is None:
+    if not os.path.exists(self.file):
       return c
+
+    d = self._do('--null', '--list')
     for line in d.rstrip('\0').split('\0'):
       if '\n' in line:
         key, val = line.split('\n', 1)