Interpretation of '/' changed sparse-checkout

I have a system where I checkout by default everything except one directory. 
Then the rules in the top-level sources can selectivly reintroduce 
subdirectories as required for the build target.
I have deployed, using git 1.7.2.5, a set of git trees which use the following 
sparse-checkout rules to achieve this.

/
!exclude/
exclude/reinclude

I have however discovered that if the reincluded directory is the same as the 
first part of any other path then that path will also be checked out.

/
!exlcude
exclude/wanted

will checkout both:

exclude/wanted
exclude/wanted_not

This appears to have bee fixed in git 1.7.10.2 but from that version of git 
onwards using '/' to request everything and then exclude a specific directory 
from it no longer works.

While I have been able to contrive the same effect with recent versions of git 
using the following updated sparse-checkout rules

/*
!exclude/
exclude/reinclude

Even with this work-around there are two problems:

1) If I have a path: exclude/reinclude/exclude, this will now be exluded where I 
would expect it to be included as it was with 1.7.2.5

2) I have a large number of deployed trees across a number of machines that have 
the existing format which will break when git operations are performed after a 
upgrade to the latest git.

I believe that the interpretation of '/' should be 'everything in the repo', 
from which later rules can exclude. I think this is a bug in recent versions of 
git. I have been working on some ideas for a fix to the git code based along 
these lines. Can anyone confirm if my analysis is correct or provide an 
alternate solution?

Also I would like to know if anyone knows the solution to point 1) above as this 
also blocks upgrading to the latest version of git.