Drastically reduce amount of API calls when checking if something exists - #1500

Drastically reduce amount of API calls when checking if something exists#1500

mdealer wants to merge 4 commits into

jenkinsci:masterjenkinsci/github-branch-source-plugin:masterfrom

mdealer:Branch_1789.v5b_0c0cea_18c3mdealer/github-branch-source-plugin:Branch_1789.v5b_0c0cea_18c3Copy head branch name to clipboard