Add Python to run-tests.
diff --git a/.gitignore b/.gitignore
index 63332d1..002e3e66 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,6 +4,9 @@
 libs
 objs
 
+# Python virtual environment (pre-3.4 only)
+python2.7_virtual_environment
+
 # gcov coverage data
 coverage
 *.gcno