Fix repo hook error upon upload

Some lines of the presubmit message are coming back as
bytes instead of a string using pyton3. So, ensure
each line is a str before checking contents.

Also, send code 77 back to ensure that the error message
is actually printed

Test: repo upload
Change-Id: Ieecd6228318b3001098ac45e4767b8bf46826387

scripts/aosp_tag_preupload.py

@@ -41,11 +41,14 @@ def main():
   commit_msg = subprocess.check_output(["git", "show",
                                         sys.argv[1], "--no-notes"])
   for commit_line in commit_msg.splitlines():
-    if re.search(AOSP_COMMIT_TAG_REGEX, commit_line, re.IGNORECASE):
-      _check_aosp_message(commit_line)
+    # Some lines in the commit message will be given to us as bytes
+    commit_line_str = str(commit_line)
+    if re.search(AOSP_COMMIT_TAG_REGEX, str(commit_line_str), re.IGNORECASE):
+      _check_aosp_message(commit_line_str)
 
   print(ERROR_MESSAGE)
-  sys.exit(0)
+  # Print the warning, but do not fail the presubmit check.
+  sys.exit(77)
 
 def _is_in_aosp():
   branch_info = subprocess.check_output(["git", "branch", "-vv"])
@@ -59,7 +62,8 @@ def _check_aosp_message(aosp_line):
     sys.exit(0)
 
   print(ERROR_MESSAGE)
-  sys.exit(0)
+  # Print the warning, but do not fail the presubmit check.
+  sys.exit(77)
 
 if __name__ == '__main__':
   main()