Jenkins-mahara: run only one feature file

(behat number fix)

jenkins/mahara_jenkins.php

@@ -301,7 +301,7 @@ echo "\n";
 
 if (($BEHATTESTNUMBER = trim(shell_exec("git diff-tree --no-commit-id --name-only -r HEAD | grep -c $BEHATTESTREGEX"))) >= 1) {
     echo "Patch includes a Behat test.\n";
-    if ($BEHATTESTNUMBER == 1) {
+    if ($BEHATTESTNUMBER === '1') {
         $BEHATTESTFEATURE = basename(trim(shell_exec("git diff-tree --no-commit-id --name-only -r HEAD | grep $BEHATTESTREGEX")));
     }
 }