subrepo: separate out mq+svn subrepo tests
Having the mq+subrepo+svn tests in a separate file lets them be skipped
without skipping the other mq+subrepo tests.
from hgext import color
# ensure errors aren't buffered
testui = color.colorui()
testui.pushbuffer()
testui.write('buffered\n')
testui.warn('warning\n')
testui.write_err('error\n')
print repr(testui.popbuffer())