Ensure git clean state after running license_finder

Our script for validating licenses does not restore
a clean git state because the whole script "scripts/license-check.sh"
is marked as "set -e" which means if any command fails with a non-zero
exit code the script terminates its execution. The failing scenario
is:
1. We start "license-check.sh" script which modifies "Gemfile.lock"
due to a workaround described inside of the script.
2. Then we run "license_finder" gem.
3. If it exits with a non-zero status code then
   the next command "git checkout -q" will never execute.

The simplest solution to resolve that failing scenario is
to capture the exit code of "license_finder" gem, store it,
restore the git clean state and exit with this exit code.

scripts/license-check.sh

@@ -18,6 +18,10 @@ set -euo pipefail
 
 PROJECT_PATH=${1:-`pwd`}
 
+function restore_git_state() {
+  git checkout -q Gemfile Gemfile.lock
+}
+
 echo "Using project path ${PROJECT_PATH}"
 
 GEMFILE_DIFF=`git diff Gemfile Gemfile.lock`
@@ -27,7 +31,7 @@ if [ ! -z "$GEMFILE_DIFF" ]; then
   exit 1
 fi
 
+trap restore_git_state EXIT
+
 BUNDLE_DEPLOYMENT=false BUNDLE_FROZEN=false bundle lock --add-platform `ruby -e "puts RUBY_PLATFORM"`
 bundle exec license_finder --decisions-file config/dependency_decisions.yml --project-path ${PROJECT_PATH}
-
-git checkout -q Gemfile Gemfile.lock