Fix the issue with temtest tests

The patch fixes the issue which appears if custom tempest
pattern is defined.

Change-Id: Ifa849673b68ad7687a77e63d18949f8de29c113e
Related-PROD: PROD-15108
diff --git a/src/com/mirantis/mk/Test.groovy b/src/com/mirantis/mk/Test.groovy
index 1c596a2..c357ae4 100644
--- a/src/com/mirantis/mk/Test.groovy
+++ b/src/com/mirantis/mk/Test.groovy
@@ -68,7 +68,7 @@
                                          "-e SOURCE_FILE=keystonercv3 " +
                                          "-e LOG_DIR=${logDir} " +
                                          "-e DO_CLEANUP_RESOURCES=${doCleanupResources} " +
-                                         "-e CUSTOM='--pattern ${pattern}' " +
+                                         "-e CUSTOM=\"--pattern ${pattern}\" " +
                                          "-v /root/:/home/rally ${dockerImageLink} >> docker-tempest.log")
     }
 }
@@ -232,4 +232,4 @@
     def salt = new com.mirantis.mk.Salt()
     salt.cmdRun(master, target, "docker stop \$(docker ps -a | grep ${image_link} | awk '{print \$1}')")
     salt.cmdRun(master, target, "docker rm \$(docker ps -a | grep ${image_link} | awk '{print \$1}')")
-}
\ No newline at end of file
+}