testsuite: Don't use git status to determine whether we are inside a repo

Git status is extremely expensive for this task. We instead use `git rev-parse
HEAD` and throw away the output to ensure we don't spam the user.

1 files changed, 5 insertions, 4 deletions

diff --git a/testsuite/driver/perf_notes.py b/testsuite/driver/perf_notes.py
index c275041252..5ceede7be2 100644
--- a/testsuite/driver/perf_notes.py
+++ b/testsuite/driver/perf_notes.py
@@ -20,11 +20,12 @@ from math import ceil, trunc
 from testutil import passed, failBecause
 
 
-# Check if "git status" can be run successfully.
+# Check if "git rev-parse" can be run successfully.
 # True implies the current directory is a git repo.
-def can_git_status():
+def inside_git_repo():
     try:
-        subprocess.check_call(['git', 'status'])
+        subprocess.check_call(['git', 'rev-parse', 'HEAD'],
+                              stdout=subprocess.DEVNULL)
         return True
     except subprocess.CalledProcessError:
         return False
@@ -388,4 +389,4 @@ if __name__ == '__main__':
 
         # Printing out percentages.
         for test, metric in all_tests:
-            print("{:27}{:30}".format(test, metric) + commit_string(test,'percentages'))
\ No newline at end of file
+            print("{:27}{:30}".format(test, metric) + commit_string(test,'percentages'))