[project @ 2003-05-26 12:30:04 by cjwatson]

[project @ 2003-05-26 12:30:04 by cjwatson]
The uses of writebug in process shouldn't unfilelock immediately; they go
on to do other things with the bug and need to hold the lock. Remove the
automatic unfilelock from writebug and introduce a new 'unlockwritebug'
function (by analogy with 'lockreadbug'), used in service.

Make unfilelock produce a more sensible error message when the @filelocks
stack is empty, in case this ever happens again.