This is a patch to the yodl documention for the zsh/system module's 
zsystem flock section to note that use of the builtin print with -u 
option has the side-effect of releasing the lock made by flock.  It also 
mentions using a sub-shell redirected to the filename as a workaround.

This should be documented since updating the file is one of the reasons 
one might use flock.