jenkins-common.sh: non-jenkins: unique build tag

Support running multiple TTCN-3 testsuites in parallel when the
jenkins.sh scripts get called from outside of jenkins too.

Closes: OS#5358
Change-Id: Iaaf5719f758553687f2ab57975be275e7ac07e36

jenkins-common.sh

@@ -438,9 +438,9 @@ if [ ! -d "$VOL_BASE_DIR" ]; then
 	exit 1
 fi
 
-# non-jenkins execution: put logs in /tmp
+# non-jenkins execution: set a unique BUILD_TAG to avoid collisions (OS#5358)
 if [ "x$BUILD_TAG" = "x" ]; then
-	BUILD_TAG=nonjenkins
+	BUILD_TAG="nonjenkins-$(date +%N)"
 fi
 
 SUITE_NAME=`basename $PWD`