During the native macOS build on Travis brew-version python update from 3.7.5 to 3.7.6_1 causes link failure:
==> Upgrading python3
==> Downloading https://homebrew.bintray.com/bottles/python-3.7.6_1.mojave.bottl
==> Downloading from https://akamai.bintray.com/64/643d627c2b4fc03a3286c397d2992
######################################################################## 100.0%
==> Pouring python-3.7.6_1.mojave.bottle.tar.gz
Error: The `brew link` step did not complete successfully
The formula built, but is not symlinked into /usr/local
Close #17848