pytorch

ca1978c9 - For jobs need a merge, merge with origin/master for ghstack PRs. (#38745)

For jobs need a merge, merge with origin/master for ghstack PRs. (#38745) Summary: ghstack PRs has target branch changed to `gh/xxx/1234/base` so the merge didn't work. Change it to `master` by default. IIRC we don't use ghstack with release branches so this should be good? cc: ezyang Pull Request resolved: https://github.com/pytorch/pytorch/pull/38745 Differential Revision: D21663796 Pulled By: ailzhang fbshipit-source-id: 3d2c7b91b0e355dc8261d8f1e7da76af8d3bcee4