hgext/convert/hg.py

--- a/hgext/convert/hg.py	Wed Jul 08 10:29:11 2015 -0700
+++ b/hgext/convert/hg.py	Wed Jul 08 10:31:09 2015 -0700
@@ -225,6 +225,10 @@
 
         extra = commit.extra.copy()
 
+        sourcename = self.repo.ui.config('convert', 'hg.sourcename')
+        if sourcename:
+            extra['convert_source'] = sourcename
+
         for label in ('source', 'transplant_source', 'rebase_source',
                       'intermediate-source'):
             node = extra.get(label)