Bug fix, IRC report.

Mesh with very strange topology makes loop-select (ALT+select) crash.
Missing NULL check for do-while loop that can return NULL.

For Campbell: here's the file to check: http://www.pasteall.org/blend/21576

1 files changed, 1 insertions, 1 deletions

diff --git a/source/blender/bmesh/intern/bmesh_walkers_impl.c b/source/blender/bmesh/intern/bmesh_walkers_impl.c
index 5f5a3f9d5b4..495f1c9648b 100644
--- a/source/blender/bmesh/intern/bmesh_walkers_impl.c
+++ b/source/blender/bmesh/intern/bmesh_walkers_impl.c
@@ -648,7 +648,7 @@ static void *bmw_LoopWalker_step(BMWalker *walker)
 			} while (true);
 		}
 
-		if (owalk.is_single == false && bm_edge_is_single(l->e)) {
+		if (owalk.is_single == false && l && bm_edge_is_single(l->e)) {
 			l = NULL;
 		}