repovfs: add a ward to check if locks are properly taken
When the appropriate developer warnings are enabled, We wrap 'repo.vfs.audit' to
check for locks when accessing file in '.hg' for writing. Another changeset will
add a 'ward' for the store vfs (svfs).
This check system has caught a handful of locking issues that have been fixed
in previous series (mostly in 4.0). I expect another batch to be caught in third
party extensions.
We introduce two real exceptions from extensions 'blackbox.log' (because a lot of
read-only operations add entry to it), and 'last-email.txt' (because 'hg email'
is currently a read only operation and there is value to keep it this way).
In addition we are currently allowing bisect to operate outside of the lock
because the current code is a bit hard to get properly locked for now. Multiple
clean up have been made but there is still a couple of them to do and the freeze
is coming.
vfs: allow to pass more argument to audit
We want to be able to do more precise check when auditing a path depending of
the intend of the file access (eg read versus write). So we now pass the 'mode'
value to 'audit' and update the audit function to accept them.
This will be put to use in the next changeset.