[$] Facing the Git commit-ID collision catastrophe

Commits in the Git source-code management system are identified by the
SHA-1 hash of their contents — though the specific hash may change someday. The full hash is a
160-bit quantity, normally written as a 40-character hexadecimal string.
While those strings are convenient for computers to work with, humans find
them to be a bit unwieldy, so it is common to abbreviate the hash values to
shorter strings. Geert Uytterhoeven recently proposed
increasing the length of those abbreviated hashes as used in the kernel
community, but the problem he was working to solve may not be as urgent as
it seems.