Rebuild for library profiling without reinstalling

[bos]

(Imported from Trac #593, reported by chevalier on 2009-09-29)

I tried:

cabal install mtl --enable-library-profiling

when I already had mtl installed, but didn't have the profiling libraries for installed. I got the message:

No packages to be installed. All the requested packages are already installed.
If you want to reinstall anyway then use the --reinstall flag.

Re-running the same command with --reinstall did install the profiling libraries, but it also rebuilt the non-profiling version (which was already installed). It would be nice if "cabal install" was smart enough to just rebuild the profiling libraries if you try to install an already-installed library with the --enable-library-profiling flag.

This is with cabal-install 0.6.2, library version 1.6.0.3.

[bos]

(Imported comment by @dcoutts on 2009-09-29)

I think the better solution is for

cabal install mtl --enable-library-profiling

To just do the right thing. That is the subject of ticket #282.