Make sure .git/info/exclude exists

Author: justafish

install.yaml

@@ -30,6 +30,7 @@ post_install_actions:
   - cp core-dev/gitignore ../vendor/.gitignore
   - cp core-dev/gitignore ../sites/simpletest/.gitignore
   - cp core-dev/gitignore ../sites/default/files/.gitignore
+  - touch .git/info/exclude
   - |
     if ! grep -q "\/sites\/default\/settings.php" ../.git/info/exclude; then
       echo "/sites/default/settings.php" >> ../.git/info/exclude