lfs: use 'ui' provided to `upgrade` for output, instead of stealing srcrepo's

Also spotted by Yuya.

hgext/lfs/wrapper.py

@@ -313,7 +313,7 b' def upgradefinishdatamigration(orig, ui,'
 
     for dirpath, dirs, files in srclfsvfs.walk():
         for oid in files:
-            srcrepo.ui.write(_('copying lfs blob %s\n') % oid)
+            ui.write(_('copying lfs blob %s\n') % oid)
             lfutil.link(srclfsvfs.join(oid), dstlfsvfs.join(oid))
 
 def upgraderequirements(orig, repo):