python 2.7 shows hangs with issues in its pool implmenetation. Rather than
try and hack around these, add a copy of the working pool implementation
to the compat module from 2.7.3.
(Bitbake rev: c9eb742637131e8dbd526d2ad9b458abea0a2d87)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>