Trim Your Inputs
Using commandline I was trying to get the current branch's ref, and achieved this using git symbolic-ref HEAD. This I had to feed it into the node application (for reasons), and ended up using the child_process.exec function. I saved the output in the application environment and called it to compare with the GitHub's push event payload's ref parameter. This failed, for obvious reasons which I later realized - I didn't prune the output that came out. A base64 showed me a trailing Cg==. :|
I've read a similar issue someone faced with Ruby where the shell output of find (?) was taken as an input to the command. This was a formatted output, with all the jingbang colors and what not, causing ridiculous symbols to appear in the middle. Lesson: When in doubt, prune your input