Diff produced by src actions exec doesn't respect gitignore

Created by: ryan-blunden

It seems that auto-generated files that are ignored by .gitignore such as schema files still make there way into a campaign plan.

To reproduce:

git clone https://github.com/sourcegraph/campaign-examples.git
cd campaign-examples/rxjs-upgrade
make exec # You may want to change the scopeQuery to just be sourcegraph
make campaign-plan

Follow the link to view the campaign plan in the UI and observe schema files in the diff ( see this example campaign on sgdemo).