[nacs]

Yeah "on crack" usually means they're not right in the head.

In this context though, OP is referring to the drug where the Github engineers are being quick/energetic about fixing the issue because they're "boosted" by the drug's effects.

[wintogreen74]

Yes, they obviously meant the more common, positive associations related to methamphetamines like, "great job on that quick PR, Kim. You must be on meth!" :)

[progrus]

Or “gee, Hunter Biden is a swell son, he sure got to Vegas really fast! He must be on crack!”