mypy_primer: speed up, clean up (#4730)

We use tee and no longer try to delete the file based on exit code,
since we use data.trim now.
mypy_primer started failing silently because of changes in aiohttp, so
now we'll fail if the exit codes are not 0 or 1.
Note mypy_primer has --project-date to get around the problem of
breaking changes in projects, but I want to try and keep mypy_primer up
to date / get a feel for how bad this problem actually is.

Co-authored-by: hauntsaninja <>

Author: hauntsaninja

.github/workflows/mypy_primer.yml

@@ -35,8 +35,7 @@ jobs:
           git rev-list --format=%s --max-count=1 upstream_master
           echo ''
           cd ..
-          ( mypy_primer --new v0.790 --old v0.790 --custom-typeshed-repo typeshed_to_test --new-typeshed $COMMIT --old-typeshed upstream_master -o concise > diff.txt && rm diff.txt ) || true
-          cat diff.txt || true
+          ( mypy_primer --new 0.790 --old 0.790 --custom-typeshed-repo typeshed_to_test --new-typeshed $COMMIT --old-typeshed upstream_master -o concise | tee diff.txt ) || [ $? -eq 1 ]
       - name: Post comment
         uses: actions/github-script@v3
         with: