What does BuildID SHA1 mean?
Or does the BuildID[sha1] refer to something else?
BuildID is NOT the hash of a binary or related to it. It is an identifier for the "build" (or compiling) session which produced that binary. It is mostly there for debug purposes, so that the developers can look at the logs, environment, etc. from session number $BuildID and try to fix the problem, reproduce it, etc.
BTW, SHA1 hashes of anything are always 160 bits long :)