dirty = the person who created the built made some local changes to the upstream source code. Basically boils down to "This build is unsupported, if you've got problems we don't care".
FIFObusy = branch build. I guess you'll want to read a bit about Git and branches to understand what that means.
FIFObusy = branch build. I guess you'll want to read a bit about Git and branches to understand what that means.