The way the OSX build jobs updates its build environment used the
"--quiet" option to "brew update" command, but it wasn't all that
quiet to be useful. The use of the option has been replaced with
an explicit redirection to the /dev/null (which incidentally would
have worked around a breakage by recent updates to homebrew, which
has fixed itself already).
* sg/travis-osx-brew-breakage-workaround:
travis-ci: make the OSX build jobs' 'brew update' more quiet
d219b7f3f9