chore(git): improve git message hook

Author: SKoschnicke

.dev/githooks/prepare-commit-msg

@@ -9,15 +9,22 @@
 # message file.  If the hook fails with a non-zero status,
 # the commit is aborted.
 #
-# To enable this hook, rename this file to "prepare-commit-msg".
+# To enable this hook, set the hooksPath in git:
+# git config core.hooksPath .dev/githooks
 
 COMMIT_MSG_FILE=$1
 COMMIT_SOURCE=$2
 SHA1=$3
 
+beginswith() { case $2 in "$1"*) true;; *) false;; esac; }
+
 original=$(cat "$COMMIT_MSG_FILE")
-printf "\n\n# Please enter the message in the format\n" > "$COMMIT_MSG_FILE"
-echo "# <type>(<scope>): <description>" >> "$COMMIT_MSG_FILE"
-echo "# Possible types: fix, feat, docs, style, refactor, test, chore, rework, release" >> "$COMMIT_MSG_FILE"
-echo "# For details see https://www.notion.so/softwarechallenge/Git-217333329ea64db5b2cc8bbbaf79db87" >> "$COMMIT_MSG_FILE"
-echo "$original" >> "$COMMIT_MSG_FILE"
+if beginswith $'\n#' "$original"; then
+    {
+        printf "\n\n# Please enter the message in the format\n"
+        echo "# <type>(<scope>): <description>"
+        echo "# Possible types: fix, feat, docs, style, refactor, test, chore, rework, release"
+        printf "# For details see https://www.notion.so/softwarechallenge/Git-217333329ea64db5b2cc8bbbaf79db87" >> "$COMMIT_MSG_FILE"
+        echo "$original"
+    } > "$COMMIT_MSG_FILE"
+fi