I've always heard it as a shorter alternative to "holy hell this tool is horrible but I'm unaware of an alternative, or cannot apply an alternative solution."
My understanding: To use something "for real" on an actual project, not just toy around with it. (What you use can be good or bad, expression doesn't say)
For what it's worth[0]:
> If you do something in anger, you do it in a real or important situation as it is intended to be done, rather than just learning or hearing about it
[0] https://dictionary.cambridge.org/dictionary/english/in-anger