FetchOne: remove unused local variable "cause"

Change-Id: I50c19da734529087c90a28de84b39da6a9dbcbe9
diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/pull/FetchOne.java b/src/main/java/com/googlesource/gerrit/plugins/replication/pull/FetchOne.java
index d8da65e..eb543a0 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/pull/FetchOne.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/pull/FetchOne.java
@@ -328,7 +328,6 @@
     } catch (NotSupportedException e) {
       stateLog.error("Cannot replicate from " + uri, e, getStatesAsArray());
     } catch (TransportException e) {
-      Throwable cause = e.getCause();
       if (e instanceof LockFailureException) {
         lockRetryCount++;
         // The LockFailureException message contains both URI and reason