Don't crash on multi-line config values

The parsing of the output of `git config --list` fails if any of the
config values contain newlines. Fix this by using the --null parameter
to `git config`, which is designed for this purpose.

Add a simple test that causes the crash pre-patch.

Signed-off-by: Toke Høiland-Jørgensen <[email protected]>

Author: tohojo

git-filter-repo

@@ -1683,14 +1683,14 @@ class GitUtils(object):
   def get_config_settings(repo_working_dir):
     output = ''
     try:
-      output = subproc.check_output('git config --list'.split(),
+      output = subproc.check_output('git config --list --null'.split(),
                                     cwd=repo_working_dir)
     except subprocess.CalledProcessError as e: # pragma: no cover
       raise SystemExit('fatal: {}'.format(e))
 
     # FIXME: Ignores multi-valued keys, just let them overwrite for now
-    return dict(line.split(b'=', maxsplit=1)
-                for line in output.strip().split(b"\n"))
+    return dict(item.split(b'\n', maxsplit=1)
+                for item in output.strip().split(b"\0") if item)
 
   @staticmethod
   def get_blob_sizes(quiet = False):

t/t9390-filter-repo-basics.sh

@@ -895,4 +895,15 @@ test_expect_success 'origin refs without origin remote does not die' '
 	)
 '
 
+test_expect_success 'multi-line config value' '
+	test_create_repo multiline_config &&
+	(
+		cd multiline_config &&
+
+		git config set test.test "test
+test" &&
+		git filter-repo --force
+	)
+'
+
 test_done