UPSTREAM: dev-lang/python: Set PYTHON_SITEDIR manually

The eclass change in fd4001e9 causes python_export to call ${PYTHON}
to obtain PYTHON_SITEDIR. This returns an empty string if ${PYTHON}
has not yet been merged.

Package-Manager: portage-2.2.23_p26

Cherry-picked from 1e379f1f1a61be360bf9cf59030e15862c2a3d21
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>

BUG=chromium:736313
TEST=PreCQ and SDK tryjob

Change-Id: I422f280999939a3b847c512598412b767320d03f
Reviewed-on: https://chromium-review.googlesource.com/1623914
Commit-Ready: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Daniel Kurtz <djkurtz@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
diff --git a/dev-lang/python/python-2.7.10.ebuild b/dev-lang/python/python-2.7.10.ebuild
index 6256de9..bd0dd0b 100644
--- a/dev-lang/python/python-2.7.10.ebuild
+++ b/dev-lang/python/python-2.7.10.ebuild
@@ -448,7 +448,8 @@
 		-i "${ED}etc/conf.d/pydoc-${SLOT}" "${ED}etc/init.d/pydoc-${SLOT}" || die "sed failed"
 
 	# for python-exec
-	python_export python${SLOT} EPYTHON PYTHON PYTHON_SITEDIR PYTHON_SCRIPTDIR
+	python_export python${SLOT} EPYTHON PYTHON PYTHON_SCRIPTDIR
+	export PYTHON_SITEDIR="${EPREFIX}/usr/$(get_libdir)/python${SLOT}/site-packages"
 
 	# if not using a cross-compiler, use the fresh binary
 	if ! tc-is-cross-compiler; then