tools: Add git utility scripts.

tools/clean-branches

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+set -e
+
+# usage: clean-branches
+# Deletes any local branches which are ancestors of origin/master,
+# and also any branches in origin which are ancestors of
+# origin/master and are named like $USER-*.
+
+# usage: clean-branches --reviews
+# Deletes all the above mentioned branches as well as branches
+# created by the scripts like `fetch-rebase-pull-request`. Be careful
+# as this would also remove other branches woth names like review-*
+
+review=0
+if [ $# -ne 0 ] && [ "$1" == "--reviews" ]; then
+    review=1
+fi
+push_args=()
+
+function is_merged {
+    ! git rev-list -n 1 origin/master.."$1" | grep -q .
+}
+
+function clean_ref {
+    ref="$1"
+    case "$ref" in
+        */master | */HEAD)
+            return
+            ;;
+
+        refs/heads/review-*)
+            if [ $review -ne 0 ]; then
+                echo -n "Deleting local branch $(echo "$ref" | sed 's!^refs/heads/!!')"
+                echo " (was $(git rev-parse --short "$ref"))"
+                git update-ref -d "$ref"
+            fi
+            ;;
+
+        refs/heads/*)
+            if is_merged "$ref"; then
+                echo -n "Deleting local branch $(echo "$ref" | sed 's!^refs/heads/!!')"
+                echo " (was $(git rev-parse --short "$ref"))"
+                git update-ref -d "$ref"
+            fi
+            ;;
+
+        refs/remotes/origin/$USER-*)
+            if is_merged "$ref"; then
+                remote_name="$(echo "$ref" | sed 's!^refs/remotes/origin/!!')"
+                echo -n "Deleting remote branch $remote_name"
+                echo " (was $(git rev-parse --short "$ref"))"
+                # NB: this won't handle spaces in ref names
+                push_args=("${push_args[@]}" ":$remote_name")
+            fi
+            ;;
+    esac
+}
+
+if [ "$(git symbolic-ref HEAD)" != 'refs/heads/master' ]; then
+    echo "Check out master before you run this script." >&2
+    exit 1
+fi
+
+git fetch --prune origin
+
+eval "$(git for-each-ref --shell --format='clean_ref %(refname);')"
+
+if [ "${#push_args}" -ne 0 ]; then
+    git push origin "${push_args[@]}"
+fi