Kokoro: Drop bug in commit message requirement

SwiftShader is not currently developing new major features, and most changes are now community contributions. Most changes do not have a corresponding Monorail issue to link against, so requiring a 'Bug:' in the commit message causes more grief than benefit.

Drop the presubmit requirement.

Change-Id: I91320814a8222f7d802525a0c3ea35efb1efd284
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/71128
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Presubmit-Ready: Ben Clayton <bclayton@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Geoff Lang <geofflang@google.com>
diff --git a/tests/presubmit.sh b/tests/presubmit.sh
index 38af885..c004689 100755
--- a/tests/presubmit.sh
+++ b/tests/presubmit.sh
@@ -40,20 +40,6 @@
   echo "${green}OK${normal}"
-# Validate commit message
-function run_bug_in_commit_msg() {
-  git log -1 --pretty=%B | grep -E '^(Bug|Issue|Fixes):(\s?)(((b\/)|(\w+:))([0-9]+)|[^0-9]+)$|(^Regres:)|(^PiperOrigin-RevId:)'
-  if [ $? -ne 0 ]
-  then
-    echo "${red}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' or 'Bug: fuchsia:123')."
-    echo "Omit any digits when no ID is required (e.g. 'Bug: fix build').${normal}"
-    return 1
-  fi
 function run_copyright_headers() {
   for suffix in "cpp" "hpp" "go" "h"; do
@@ -93,9 +79,6 @@
 # Ensure we are clean to start out with.
 check "git workspace must be clean" true
-# Check for 'Bug: ' line in commit
-check bug-in-commi-msg run_bug_in_commit_msg
 # Check copyright headers
 check copyright-headers run_copyright_headers