2015-02-20 11:20 AEST by Arthur Barrett - svn apparently will do all the 'pre-commit' checking before commencing the first commit, whereas CVS 
does it on a per-file basis, so if there are commit file markers left in the last file - all files are committed 
except the last one, or if all the files are 'up to date' except the last one, ditto.

This gives users the 'impression' that SVN commits are atomic (which they are not).

CVS of course can do this - it's called 'dry run' with cvs -n commit.  However we've dropped support for '-
n' a loooooong time ago.  We could try and (at least partially) re-enable this, or have an option just for 
commit which does the commit in three steps:
1) dry run commit - deadlock all affected RCS files
2) if no errors, do the commit
3) release the deadlocks