ci: force install/link bazelisk package in macos dependency setup (#1…

…0357)

Latest mac os images have bazel pre-installed so force install bazelisk and link with overwrite to allow install to succeed

Risk Level: Low
Testing: N/A
Docs Changes: N/A
Release Notes: N/A

Co-authored-by: Sunjay Bhatia <sbhatia@pivotal.io>
Co-authored-by: William A Rowe Jr <wrowe@pivotal.io>
Signed-off-by: Sunjay Bhatia <sbhatia@pivotal.io>
Signed-off-by: William A Rowe Jr <wrowe@pivotal.io>

ci/mac_ci_setup.sh

@@ -2,18 +2,17 @@
 
 # Installs the dependencies required for a macOS build via homebrew.
 # Tools are not upgraded to new versions.
-
-# Setup bazelbuild tap
-brew tap bazelbuild/tap
+# See:
+# https://github.com/actions/virtual-environments/blob/master/images/macos/macos-10.15-Readme.md for
+# a list of pre-installed tools in the macOS image.
 
 function is_installed {
     brew ls --versions "$1" >/dev/null
 }
 
 function install {
     echo "Installing $1"
-    if ! brew install "$1"
-    then
+    if ! brew install "$1"; then
         echo "Failed to install $1"
         exit 1
     fi
@@ -24,7 +23,7 @@ if ! brew update; then
     exit 1
 fi
 
-DEPS="automake bazelbuild/tap/bazelisk cmake coreutils go libtool wget ninja"
+DEPS="automake cmake coreutils go libtool wget ninja"
 for DEP in ${DEPS}
 do
     is_installed "${DEP}" || install "${DEP}"
@@ -35,3 +34,12 @@ if [ -n "$CIRCLECI" ]; then
     # convert https://github.com to ssh://git@github.com, which jgit does not support.
     mv ~/.gitconfig ~/.gitconfig_save
 fi
+
+# Required as bazel and a foreign bazelisk are installed in the latest macos vm image, we have
+# to unlink/overwrite them to install bazelisk
+echo "Installing bazelbuild/tap/bazelisk"
+brew install --force bazelbuild/tap/bazelisk
+if ! brew link --overwrite bazelbuild/tap/bazelisk; then
+    echo "Failed to install and link bazelbuild/tap/bazelisk"
+    exit 1
+fi