Make the release notes script tolerant of merges

This makes the release notes script tolerant of manual merges, which
helps when calculating the release notes before doing the GitHub branch
merge.

Author: DirectXMan12

hack/release/release-notes.sh

@@ -21,7 +21,16 @@ NEWLINE="
 "
 head_commit=$(git rev-parse HEAD)
 while read commit_word commit; do
+    if [[ -z ${commit_word} ]]; then
+        # skip terminating blank lines
+        continue
+    fi
     read title
+    if [[ ${title} == "Merge branch '"*"' into release-"* ]]; then
+        # skip temporary merge commits for calculating release notes
+        continue
+    fi
+
     read # skip the blank line
     read prefix body