Retry brew update to fix errors about another active Homebrew process…

… being active (#1032)

Signed-off-by: Addisu Z. Taddese <[email protected]>

jenkins-scripts/lib/_homebrew_base_setup.bash

@@ -16,7 +16,15 @@ fi
 
 git -C $(${BREW_BINARY} --repo) fsck
 export HOMEBREW_UPDATE_TO_TAG=1
-${BREW_BINARY} update
+
+# There might be a background process that blocks `brew update`, so we try to
+# run it several times until it succeeds.
+# See https://github.com/Homebrew/brew/issues/1155
+brew_update_retry_count=0
+until ${BREW_BINARY} update || (( brew_update_retry_count++ > 6 ))
+do
+  sleep 10
+done
 # manually exclude a ruby warning that jenkins thinks is from clang
 # https://github.com/osrf/homebrew-simulation/issues/1343
 ${BREW_BINARY} install ${BREW_BASE_DEPENDCIES} \