Reduced output of virtualenv commands in Jenkins

Change-Id: I4a5f4de06259c5b7e7f9f9bdbaf52b549994b085
diff --git a/src/com/mirantis/mk/Python.groovy b/src/com/mirantis/mk/Python.groovy
index 2b51681..6e0655e 100644
--- a/src/com/mirantis/mk/Python.groovy
+++ b/src/com/mirantis/mk/Python.groovy
@@ -56,7 +56,7 @@
 def runVirtualenvCommand(path, cmd) {
     def common = new com.mirantis.mk.Common()
 
-    virtualenv_cmd = ". ${path}/bin/activate > /dev/null; ${cmd}"
+    virtualenv_cmd = "set +x; . ${path}/bin/activate; ${cmd}"
     common.infoMsg("[Python ${path}] Run command ${cmd}")
     output = sh(
         returnStdout: true,