site_scons is not respected for Repository

[mwichmann]

Filed so the issue is recorded, need to discuss what (if anything) to do about:

If you use a repository (-Y flag or env.Repository call), items from site_scons are not pulled from the repository even if they don't exist in the working directory. A simple thought example is a site_init.py in a repository repo.d that sets a constant FOO to customize the build, have the SConstruct file reference FOO and then invoke scons in an empty directory like:

scons -Y ../repo.d

You'll get an error like:

NameError: name 'FOO' is not defined:
...

This would be the case for SCons itself, which sets constants this way (gzip, git, etc.)

Should scons look for site_init.py in the repository if it didn't find it in the regular site_scons? If so, should it also look for tools in site_scons/site_tools?