Allow verbal bug IDs

In rare cases the requirement to have a Buganizer or Monorail bug ID
in the commit message can be unreasonable. For example when the build
is broken and the fix is trivial so the creation of a tracker bug would
needlessly take valuable time. Another example would be fixing a
spelling mistake in a comment and we don't want to spam the tracker
thread with a commit notification.

For such cases, accept bug info lines containing no digits.

Bug: b/141892461
Change-Id: Iaf44eb3dfc08d3e138fe8ba24501fa9c046d36de
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/40029
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>

tests/presubmit.sh

diff --git a/tests/presubmit.sh b/tests/presubmit.sh
index 87ac54c..4ba0d16 100755
--- a/tests/presubmit.sh
+++ b/tests/presubmit.sh
@@ -40,13 +40,14 @@
 
 # Validate commit message
 function run_bug_in_commit_msg() {
-  git log -1 --pretty=%B | grep -E '^(Bug|Issue|Fixes):(\s?)((b\/)|(\w+:))([0-9]+)$|(^Regres:)'
+  git log -1 --pretty=%B | grep -E '^(Bug|Issue|Fixes):(\s?)(((b\/)|(\w+:))([0-9]+)|[^0-9]+)$|(^Regres:)'
 
   if [ $? -ne 0 ]
   then
     echo "Git commit message must have a Bug: line"
     echo "followed by a bug ID in the form b/# for Buganizer bugs or"
     echo "project:# for Monorail bugs (e.g. 'Bug: chromium:123')."
+    echo "Omit any digits when no ID is required (e.g. 'Bug: fix build')."
     return 1
   fi
 }