Build tool overriding site specific changes on pantheon.

[sandipsmarty]

Scenario:
I have pushed few commits on a site specific repo on Pantheon. Then pushed couple of commits into develop branch of Github upstream repo and merged back the develop changes into master on upstream via a PR. After the successful completion of the master branch build, I observed all my previous site specific commits on master branch on pantheon repo disappeared. Most probably build tool is force pushing without considering downstream site changes.

This is an critical issue and should be fixed asap.

For better understanding of the issue, please refer the screenshots below to compare the commit history before and after the master branch build by build tool.