Description
On some scheduled jobs on macOS, since a few hours the brew update and brew upgrade commands are failing.

Area for Triage:

Question, Bug, or Feature?:
Bug

Virtual environments affected

• Ubuntu 16.04
• Ubuntu 18.04
• Ubuntu 20.04
• macOS 10.15
• macOS 11.0
• Windows Server 2016 R2
• Windows Server 2019

Expected behavior
The commands:

• brew update
• brew upgrade

Should work fine.

Actual behavior

• brew update
• brew upgrade
  commands fail with error:

2020-12-11T14:20:31.2785670Z �[34m==>�[0m �[1mPouring openssl@1.1-1.1.1i.catalina.bottle.tar.gz�[0m
2020-12-11T14:21:54.9827160Z �[31mError:�[0m Not a directory @ dir_s_rmdir - /usr/local/Cellar/openssl
2020-12-11T14:21:54.9844860Z �[34m==>�[0m �[1mCaveats�[0m

See for example https://github.com/robotology/robotology-superbuild/runs/1534684566?check_suite_focus=true .

Repro steps
A description with steps to reproduce the issue. If your have a public example or repo to share,
please provide the link.

1. Run brew update
2. Run brew upgrade