From d0d19f97cfcae7e7115d1efe8eb7933d9a88e14c Mon Sep 17 00:00:00 2001
From: Eliot Horowitz <eliot@10gen.com>
Date: Sat, 7 Nov 2009 21:00:15 -0500
Subject: [PATCH] handle edge case

---
 db/mr.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/db/mr.cpp b/db/mr.cpp
index a0583ee22e4..e19940e877d 100644
--- a/db/mr.cpp
+++ b/db/mr.cpp
@@ -149,8 +149,10 @@ namespace mongo {
                 if ( finalLong != tempLong ){
                     dblock l;
                     db.dropCollection( finalLong );
-                    BSONObj info;
-                    uassert( "rename failed" , db.runCommand( "admin" , BSON( "renameCollection" << tempLong << "to" << finalLong ) , info ) );
+                    if ( db.count( tempLong ) ){
+                        BSONObj info;
+                        uassert( "rename failed" , db.runCommand( "admin" , BSON( "renameCollection" << tempLong << "to" << finalLong ) , info ) );
+                    }
                 }
                 return db.count( finalLong );
             }