Release notes test small fixes

 - Avoid trap being called when grep is not matching (|| true)
 - Ensure we always start in master branch

Change-Id: I7a71abbdfae7dc2b9680e769ed0322a6a12221dc
PiperOrigin-RevId: 172316454
diff --git a/scripts/release/relnotes.sh b/scripts/release/relnotes.sh
index 1f2493b..e72d3d4 100755
--- a/scripts/release/relnotes.sh
+++ b/scripts/release/relnotes.sh
@@ -61,12 +61,12 @@
   shift
   local cherry_picks="$@"
   local rollback_commits=$(git log --oneline -E --grep='^Rollback of commit [a-z0-9]+.$' ${baseline}.. \
-      | grep -E '^[a-z0-9]+ Rollback of commit [a-z0-9]+.$')
+      | grep -E '^[a-z0-9]+ Rollback of commit [a-z0-9]+.$' || true)
   local rollback_hashes=$(echo "$rollback_commits" | cut -d " " -f 1)
   local rolledback_hashes=$(echo "$rollback_commits" | cut -d " " -f 5 | sed -E 's/^(.......).*$/\1/')
   local exclude_hashes=$(echo $cherry_picks $rollback_hashes $rolledback_hashes | xargs echo | sed 's/ /|/g')
   git log --reverse --pretty=format:%H ${baseline}.. -E --grep='^RELNOTES(\[[^\]+\])?:' \
-      | grep -Ev "^(${exclude_hashes})"
+      | grep -Ev "^(${exclude_hashes})" || true
 }
 
 # Extract the release note from a commit hash ($1). It extracts
diff --git a/scripts/release/relnotes_test.sh b/scripts/release/relnotes_test.sh
index 0cf42b4..a3c8ceb 100755
--- a/scripts/release/relnotes_test.sh
+++ b/scripts/release/relnotes_test.sh
@@ -31,6 +31,7 @@
 
 function set_up() {
   cd ${MASTER_ROOT}
+  git checkout -q master
 }
 
 function test_format_release_notes() {