Should BuildSystem download updated external packages when they are out of date?

[Richard Tran Mills]

BuildSystem Folks (Matt, mainly),

This is not really a problem for me since I know about this behavior already, 
but I note that it can cause significant confusion when configure.py has been 
asked to download a package and a very out of date version of that package 
already exists in $PETSC_DIR/externalpackages.  In this case, configure.py 
doesn't do anything since the package is already there, but in some cases the 
interfaces have changed and that package isn't actually usable.  For instance, 
if hypre-2.0.0 is present, it won't work with the current petsc-dev, but the 
configure proceeds anyway, even though things won't work unless hypre-2.4.0b 
is downloaded.  In such a case, deleting the hypre-2.0.0 directory and 
re-running configure.py will fix the problem, but it seems like this isn't 
very user-friendly and I know that it does cause some confusion.

I am no BuildSystem hacker (I think I've committed a change maybed once, in 
2005?).  Can someone tell me if it is reasonable to make configure.py download 
the new package if the old one is too out of date?

Sincerely,
Richard