start-commit — Notification of the beginning of a commit.
The start-commit hook is run before the commit transaction is even created. It is typically used to decide whether the user has commit privileges at all.
If the start-commit hook program returns a nonzero exit
value, the commit is stopped before the commit transaction
is even created, and anything printed to
marshalled back to the client.
The command-line arguments passed to the hook program, in order, are:
Authenticated username attempting the commit
Colon-separated list of capabilities that a client passes to the server, including
log-revprops(new in Subversion 1.5).