[yelp] yelp-mallard-document: Don't start transform if running

[Shaun McCance <shaunm src gnome org>]

commit efca6e980bc4d07c7ef698c34a96ada9e827075d
Author: Shaun McCance <shaunm gnome org>
Date:   Fri May 6 10:00:49 2011 -0400

    yelp-mallard-document: Don't start transform if running

 libyelp/yelp-mallard-document.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/libyelp/yelp-mallard-document.c b/libyelp/yelp-mallard-document.c
index 6b21e5d..2c62a7f 100644
--- a/libyelp/yelp-mallard-document.c
+++ b/libyelp/yelp-mallard-document.c
@@ -429,6 +429,11 @@ mallard_try_run (YelpMallardDocument *mallard,
         return;
     }
 
+    if (page_data->transform != NULL) {
+        /* It's already running. Just let it be. */
+        return;
+    }
+
     mallard_page_data_run (page_data);
 }