Improved setting error messages to jenkins job descriptions

Change-Id: Ia19224b7334d6fd468ecc40be87d5b4df795adc5
diff --git a/git-merge-branches-pipeline.groovy b/git-merge-branches-pipeline.groovy
index 0d8c47b..8293f87 100644
--- a/git-merge-branches-pipeline.groovy
+++ b/git-merge-branches-pipeline.groovy
@@ -22,7 +22,7 @@
   } catch (Throwable e) {
      // If there was an error or exception thrown, the build failed
      currentBuild.result = "FAILURE"
-     currentBuild.description = e.message
+     currentBuild.description = currentBuild.description ? e.message + " " + currentBuild.description : e.message
      throw e
   }
 }