--no-skip doesn't work anymore

[alangpierce]

I was seeing ghstack skip some PRs that I wanted to update, so I tried running --no-skip on ghstack 0.9.3, but it still skipped the PRs. From a quick look through the code, it looks like maybe --no-skip support was removed by accident when reworking the code for 0.9.0.

[alangpierce]

For context on why I wanted --no-skip, it can come up when merging multiple PRs in a row with nobody else merging changes in between. Normally I land the bottom PR by updating the base branch and merging, then I rebase and ghstack so the new bottom PR is based off of the newly-updated default branch. If nobody else has landed anything during this time, though, the second ghstack is treated as a no-op, so I don't get an updated base. The workaround has been to run ghstack with --no-skip to ensure the base gets updated.

[ezyang]

Oops. I thought I had fixed this bug but apparently not. Thanks for the report.