Don't error if no errors are found

Previously, as we had set -e enabled, the final grep (filtering relevant
errors) would fail if there were no errors to find. This failure was
causing the script to exit with an error code (causing the CI to think
the lint had failed). Now we ignore whether the grep fails or not.

Author: thk123

scripts/run_lint.sh

@@ -74,7 +74,7 @@ for file in $diff_files; do
   # Run the linting script and filter by the filter we've build
   # of all the modified lines
   # The errors from the linter go to STDERR so must be redirected to STDOUT
-  result=`python scripts/cpplint.py $file 2>&1 | grep -E "$lint_grep_filter"`
+  result=`python scripts/cpplint.py $file 2>&1 | { grep -E "$lint_grep_filter" || true; }`
 
   # Providing some errors were relevant we print them out
   if [ "$result" ]