fix: File enumeration fails on older git binary

Signed-off-by: George Pickering <[email protected]>

detect_secrets/core/baseline.py

@@ -361,22 +361,38 @@ def _get_git_tracked_files(rootdir='.'):
     :returns: filepaths to files which git currently tracks (locally)
     """
     output = []
+    git_dir_opts = []
     try:
         with open(os.devnull, 'w') as fnull:
-            git_files = subprocess.check_output(
+            # git <1.8.5 https://github.com/git/git/commit/44e1e4d67d5148c245db362cc48c3cc6c2ec82ca
+            # doesn't support -C <path>
+            git_major, git_minor, git_patch, _ = subprocess.check_output(
                 [
                     'git',
-                    '-C', rootdir,
-                    'ls-files',
+                    '--version',
                 ],
                 stderr=fnull,
+            ).decode('utf-8').split()[-1].split(".")
+
+            if int(git_major) == 1 and int(git_minor) <= 8 and int(git_patch) < 5:
+                git_dir_opts = ["--git-dir", os.path.join(rootdir, ".git")]
+            else:
+                git_dir_opts = ["-C", rootdir]
+
+            git_files = subprocess.check_output(
+                ['git' ] + git_dir_opts + ['ls-files'],
+                stderr=fnull,
             )
         for filename in git_files.decode('utf-8').split():
             relative_path = util.get_relative_path_if_in_cwd(rootdir, filename)
             if relative_path:
                 output.append(relative_path)
-    except subprocess.CalledProcessError:
+
+    except subprocess.CalledProcessError as err:
+        log.error('detect-secrets: Encountered error trying to list git tracked '+
+                  f'files for dir "{rootdir}": {str(err)}')
         pass
+
     return output