macOS Homebrew CI is failing

[traversaro]

Similar to #565, the CI is now failing with:

2021-01-05T15:48:44.8228350Z �[34m==>�[0m �[1mPouring [email protected]_1.catalina.bottle.tar.gz�[0m
2021-01-05T15:48:50.8478390Z �[31mError:�[0m The `brew link` step did not complete successfully
2021-01-05T15:48:50.8479120Z The formula built, but is not symlinked into /usr/local
2021-01-05T15:48:50.8483440Z Could not symlink bin/c++-9
2021-01-05T15:48:50.8484230Z Target /usr/local/bin/c++-9
2021-01-05T15:48:50.8485440Z is a symlink belonging to gcc@9. You can unlink it:
2021-01-05T15:48:50.8485930Z   brew unlink gcc@9
2021-01-05T15:48:50.8486170Z 
2021-01-05T15:48:50.8486600Z To force the link and overwrite all conflicting files:
2021-01-05T15:48:50.8487530Z   brew link --overwrite gcc@9
2021-01-05T15:48:50.8487820Z 
2021-01-05T15:48:50.8488190Z To list all files that would be deleted:
2021-01-05T15:48:50.8489020Z   brew link --overwrite --dry-run gcc@9
2021-01-05T15:48:50.8489340Z 
2021-01-05T15:48:50.8489710Z Possible conflicting files are:
2021-01-05T15:48:50.8490630Z /usr/local/bin/c++-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/c++-9
2021-01-05T15:48:50.8493490Z /usr/local/bin/cpp-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/cpp-9
2021-01-05T15:48:50.8497350Z /usr/local/bin/g++-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/g++-9
2021-01-05T15:48:50.8500770Z /usr/local/bin/gcc-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/gcc-9
2021-01-05T15:48:50.8504730Z /usr/local/bin/gcc-ar-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/gcc-ar-9
2021-01-05T15:48:50.8508080Z /usr/local/bin/gcc-nm-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/gcc-nm-9
2021-01-05T15:48:50.8511890Z /usr/local/bin/gcc-ranlib-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/gcc-ranlib-9
2021-01-05T15:48:50.8515360Z /usr/local/bin/gcov-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/gcov-9
2021-01-05T15:48:50.8520890Z /usr/local/bin/gcov-dump-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/gcov-dump-9
2021-01-05T15:48:50.8522450Z /usr/local/bin/gcov-tool-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/gcov-tool-9
2021-01-05T15:48:50.8526520Z /usr/local/bin/gfortran-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/gfortran-9
2021-01-05T15:48:50.8530890Z /usr/local/bin/x86_64-apple-darwin19-c++-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/x86_64-apple-darwin19-c++-9
2021-01-05T15:48:50.8534470Z /usr/local/bin/x86_64-apple-darwin19-g++-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/x86_64-apple-darwin19-g++-9
2021-01-05T15:48:50.8537740Z /usr/local/bin/x86_64-apple-darwin19-gcc-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/x86_64-apple-darwin19-gcc-9
2021-01-05T15:48:50.8541460Z /usr/local/bin/x86_64-apple-darwin19-gcc-9.3.0 -> /usr/local/Cellar/gcc@9/9.3.0/bin/x86_64-apple-darwin19-gcc-9.3.0
2021-01-05T15:48:50.8545370Z /usr/local/bin/x86_64-apple-darwin19-gcc-ar-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/x86_64-apple-darwin19-gcc-ar-9
2021-01-05T15:48:50.8548840Z /usr/local/bin/x86_64-apple-darwin19-gcc-nm-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/x86_64-apple-darwin19-gcc-nm-9
2021-01-05T15:48:50.8552670Z /usr/local/bin/x86_64-apple-darwin19-gcc-ranlib-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/x86_64-apple-darwin19-gcc-ranlib-9
2021-01-05T15:48:50.8556370Z /usr/local/bin/x86_64-apple-darwin19-gfortran-9 -> /usr/local/Cellar/gcc@9/9.3.0/bin/x86_64-apple-darwin19-gfortran-9

[traversaro]

Upstream issue: actions/runner-images#2391 .

[traversaro]

A workaround was added in #573 .

[traversaro]

The workaround was removed in #702 .