fix crash cancelling msg copy operation, r=neil.parkwaycc.co.uk, sr=sspitzer

mailnews/base/src/nsMsgCopyService.cpp

@@ -287,11 +287,17 @@ nsMsgCopyService::DoNextCopy()
           }
           else if (copyRequest->m_requestType == nsCopyFoldersType )
           {
-			        copySource->m_processed = PR_TRUE;
+              copySource->m_processed = PR_TRUE;
               rv = copyRequest->m_dstFolder->CopyFolder
                   (copySource->m_msgFolder,
                    copyRequest->m_isMoveOrDraftOrTemplate,
                    copyRequest->m_msgWindow, copyRequest->m_listener);
+              // If it's a copy folder operation and the destination
+              // folder already exists, CopyFolder() returns an error w/o sending
+              // a completion notification, so clear it here.
+              if (NS_FAILED(rv))
+                ClearRequest(copyRequest, rv);
+
           }
           else if (copyRequest->m_requestType == nsCopyFileMessageType)
           {
@@ -318,14 +324,6 @@ nsMsgCopyService::DoNextCopy()
           }
       }
     }
-    // Don't clear copy request in failure case - notify completion should do that.
-    // Hmm, this is not true in case it's a copy folder opeation and the destination
-    // folder already exists. In this case CopyFolder() returns an error and there
-    // won't be completion notification at all and the request will stay in the
-    // queue forever.
-    if (NS_FAILED(rv))
-      ClearRequest(copyRequest, rv);
-
     return rv;
 }