VOL-1996 v2 - escape $ properly in shell scripts inside Groovy pipelines

Change-Id: Ifa3490ff121ef27d17b58bdd53c8e4bb942e401e
diff --git a/jjb/pipeline/docker-publish.groovy b/jjb/pipeline/docker-publish.groovy
index 2b55663..b864af4 100644
--- a/jjb/pipeline/docker-publish.groovy
+++ b/jjb/pipeline/docker-publish.groovy
@@ -65,7 +65,7 @@
             for tag in $git_tags
             do
               # remove leading 'v' on funky golang tags
-              clean_tag=$(echo \$tag | sed 's/^v//g')
+              clean_tag=\$(echo \$tag | sed 's/^v//g')
               echo "Building image with tag: \$clean_tag (should reuse cached layers)"
               make DOCKER_TAG="\$clean_tag" docker-build
             done
@@ -101,7 +101,7 @@
                 for tag in $git_tags
                 do
                   # remove leading 'v' on funky golang tags
-                  clean_tag=$(echo \$tag | sed 's/^v//g')
+                  clean_tag=\$(echo \$tag | sed 's/^v//g')
                   echo "Pushing image with tag: \$clean_tag (should reuse cached layers)"
                   make DOCKER_TAG="\$clean_tag" docker-push
                 done