hgweb.unbundle: call req.httphdr only after the last possible call to bail

mercurial/hgweb/hgweb_mod.py

@@ -1076,8 +1076,6 b' class hgweb(object):'
                  headers={'status': '401 Unauthorized'})
             return
 
-        req.httphdr("application/mercurial-0.1")
-
         their_heads = req.form['heads'][0].split(' ')
 
         def check_heads():
@@ -1089,6 +1087,8 b' class hgweb(object):'
             bail(_('unsynced changes\n'))
             return
 
+        req.httphdr("application/mercurial-0.1")
+
         # do not lock repo until all changegroup data is
         # streamed. save to temporary file.