fix: only run postinstall if .git exists

Author: Marcy Sutton

bin/postinstall.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+if [ -d ".git" ]; then
+	if [ ! -f ".git/hooks/commit-msg" ]; then
+		echo "Installing pre-commit hook"
+		cd .git/hooks/ && cp ../../node_modules/angular-precommit/index.js commit-msg && cd ../../
+	fi
+fi

package.json

@@ -52,7 +52,7 @@
     "test-fast": "grunt test-fast",
     "version": "node build/sri-update",
     "prepublishOnly": "grunt build && node build/sri-update --validate",
-    "postinstall": "cd .git/hooks/ && cp ../../node_modules/angular-precommit/index.js commit-msg && cd ../../"
+    "postinstall": "./bin/postinstall.sh"
   },
   "devDependencies": {
     "angular-precommit": "^1.0.3",