Fix copyright checker

The have_err variable was unset after the loop as it ran in a subshell.

Author: TimoWilken

.github/workflows/code-formatting.yml

@@ -130,17 +130,16 @@ jobs:
           // granted to it by virtue of its status as an Intergovernmental Organization
           // or submit itself to any jurisdiction.
       run: |
-        set -exo pipefail
         # Run copyright notice check
         copyright_lines=$(echo "$COPYRIGHT" | wc -l)
         base_commit=$(git merge-base HEAD ${{ github.event.pull_request.base.sha }})
         have_err=
-        git diff --diff-filter d --name-only "$base_commit" -- '*.cxx' '*.h' | while read -r file; do
+        while read -r file; do
           if [ "$(head -n "$copyright_lines" "$file")" != "$COPYRIGHT" ]; then
             echo "::error::$file: missing or malformed copyright notice" >&2
             have_err=1
           fi
-        done
+        done < <(git diff --diff-filter d --name-only "$base_commit" -- '*.cxx' '*.h')
 
         # Tell user what to do in case of copyright notice error
         if [ -n "$have_err" ]; then