[p4] Syncing only to labeled files using p4 command line

[Ken.Williams@thomson.com]

Hi,

This strikes me as a question I should probably already know the answer
to, but I couldn't seem to find it from perusing the Tech Notes on
labels, or the section of Chapter 6 in the docs on labels.

I've got a label called "LastWorkingRevision", which is a light-weight
way for our developers to indicate the last working revision of a set of
files they're working on when they know the head revision is broken.
The idea is that if syncing to head & building & testing fails, team
members should be able to sync to head then sync to this label and
probably get a working build.

Using p4win, we can sync to head, then right-click on the label and
select "sync specific files to label" to achieve this effect.  Using the
p4 command-line client (on Linux) though, I'm not sure what the easiest
way is.  If we do "p4 sync ... at LastWorkingRevision", all files not
mentioned in the label are deleted.

Any tips?

 -Ken