Don't enable dk.brics.automaton's optional syntax

Specifically we don't want "@" to mean "any string".  Some people
like to use "@" in a reference name such as "dev@cust1" and
"dev@cust2".

Change-Id: I401fa7cdfd1534690866f0e390e27447782bc5c9
Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/project/RefControl.java b/gerrit-server/src/main/java/com/google/gerrit/server/project/RefControl.java
index 2c20161..46fd90e 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/project/RefControl.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/project/RefControl.java
@@ -576,6 +576,6 @@
     if (isRE(refPattern)) {
       refPattern = refPattern.substring(1);
     }
-    return new RegExp(refPattern);
+    return new RegExp(refPattern, RegExp.NONE);
   }
 }