Command line option for skipping part of the script

[hiker]

During debugging, I often don't need to do a checkout of dependencies (um, ukca, ...), or run the configurator again. I typically comment out these calls then.

It would be convenient if we had a command line option(s) to:

• skip any git/svn/fcm checkout
• configurator (ok, I wrote: "and maybe even file find" - that's stupid, file_find fills the artefact store :) )

[hiker]

Additional suggestion: maybe the directories in which some dependencies are checked out could get a 'version' number. E.g. instead of checking out to science/jules, we would check out to science/jules-29007. This way we could handle this much better:
if the directory already exists, don't clone. If a directory with a different version exists, we could:

• abort with a warning (leaving it to the user to remove it) or
• even remove it (though one could argue about potential risks if a script recursively deletes files - any bug could seriously affect a user)
• Maybe automatically ignore this directory in Fab (with a specific user warning)?