[gentoo-science] can't emerge sage because a dependency is not in portage

[sitquietly]

For the past several weeks I've found it impossible to emerge sage from the 
sage-on-gentoo overlay because the ebuild for sage-5.2 (~amd64) and 
sage-5.3_beta2 (masked) requires ~dev-python/networkx-1.6.  However 
networkx-1.6 is not in portage any longer; networkx-1.2 is in the overlay and 
networkx-1.7 is in portage.

sage-5.1 had a networkx-1.6 specific patch but I don't see any patches in 
sage-5.2 that are networkx specific.

Should I copy the sage ebuild into my local overlay and change the dependency 
to networkx-1.7?  I'd be glad to be warned if any one knows of any problem I 
would encounter before I invest the time to try emerging sage to use the newer 
version of networkx.

I also was wondering why dev-python/networkx is required; I thought that 
networkx was integrated into sage?