UPSTREAM: dev-lang/python: Fix py version ref for python_export in 2.7

Cherry-picked from f1d0291c21447855d4cbe517fc0b182f4a02d72b
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>

BUG=chromium:736313
TEST=PreCQ and SDK tryjob

Change-Id: I9df279f580d6706a94c133834fec3c9abc6f8e7f
Reviewed-on: https://chromium-review.googlesource.com/1623916
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 9b468da..accd5a7 100644
--- a/dev-lang/python/python-2.7.10.ebuild
+++ b/dev-lang/python/python-2.7.10.ebuild
@@ -458,7 +458,7 @@
 		vars=( PYTHON "${vars[@]}" )
 	fi
 
-	python_export "python${PYVER}" "${vars[@]}"
+	python_export "python${SLOT}" "${vars[@]}"
 	echo "EPYTHON='${EPYTHON}'" > epython.py || die
 	python_domodule epython.py