Revert 60652.
The 'alias' rule passes 'no-rename' to main-target-sources,
and targets.create-metatarget does not, presently, support
that. As result:
alias a :
[ python-extension xxx ]
[ bpl-test yyy : xxx ]
;
Does not work since 'xxx' gets renamed to a..xxx.
We obviously need to handle 'no-rename', but for now,
just revert the patch.