Display module paths in the UI

I'm using one drupal codebase to develop several sites. I find it useful to be able to override a module on a per-site basis. Here's how I'm doing it:

This is a truncated version of my drupal codebase:

drupal/
    ...
    modules/
        ...
        some.module
    ...
    sites/
        site1/
            settings.php
        site2/
            settings.php
            modules/
                some.module
        site3/
            settings.php
    ...

My sites/site2/modules/some.module replaces modules/some.module. This means that site1 and site3 can use the original some.module, while site2 can have some customised behaviour.

This doesn't work by default in drupal, as modules/some.module will be loaded instead of sites/site2/modules/some.module, but it only takes a small change in bootstrap.inc, a patch of which I have attached. This may not be the best way to implement this change because it's very subtle and should probably be more explicit about what it's doing, but it's a nice quick fix.

Of course I could just call my custom module sites/site2/modules/someother.module and avoid the whole problem, but that makes quickly customising a module tedious, because after copying the module I have to go through it and replace most (but not all) instances of 'some' with 'someother'.

This also raises issues when some.module gets updated, because I now have to maintain my own modified some.module separately, but I am going to have to do this anyway to implement some features that only make sense in site2, and nowhere else. Until I can override individual functions of a module (like I can with theme_ functions), this seems like the best solution.