[plt-scheme] PLanetT development links

It looks as if regular PLaneT packages in the local cache override  
development links installed by the programmer. Is this the intended  
behaviour? It seems as if it would be useful to override a cached  
package to work on it without getting rid of it (i.e. the development  
link ought to override the cached package instead).

It's no big deal - I can always do "planet -r" to the offending  
package - just a thought.

Cheers,

-- Dave