Fix an error leak. Analogous to the one fixed in r30398.

* subversion/libsvn_client/merge.c
  (merge_dir_deleted): Always clear the "failed to delete" error.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@872509 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/subversion/libsvn_client/merge.c b/subversion/libsvn_client/merge.c
index f4d1e82..9e6a79e 100644
--- a/subversion/libsvn_client/merge.c
+++ b/subversion/libsvn_client/merge.c
@@ -1280,9 +1280,10 @@
                                     merge_b->dry_run, FALSE,
                                     NULL, NULL,
                                     merge_b->ctx, subpool);
-        if (err && state)
+        if (err)
           {
-            *state = svn_wc_notify_state_obstructed;
+            if (state)
+              *state = svn_wc_notify_state_obstructed;
             svn_error_clear(err);
           }
         else if (state)