set git repository form buildkite environment
diff --git a/buildkite/bazelci.py b/buildkite/bazelci.py
index 949e7ae..d3f330c 100644
--- a/buildkite/bazelci.py
+++ b/buildkite/bazelci.py
@@ -302,6 +302,8 @@
     try:
         if git_repository:
             clone_git_repository(git_repository, platform)
+        else:
+            git_repository = os.getenv("BUILDKITE_REPO")
         cleanup()
         tmpdir = tempfile.mkdtemp()
         if use_but: