diff -r f7b8b4ae2d25 -r 89ce95f907bd mercurial/hgweb/hgweb_mod.py
--- a/mercurial/hgweb/hgweb_mod.py	Tue Jun 09 12:57:57 2015 -0400
+++ b/mercurial/hgweb/hgweb_mod.py	Sun Jun 07 17:14:17 2015 -0700
@@ -69,6 +69,10 @@
         r.baseui.setconfig('ui', 'report_untrusted', 'off', 'hgweb')
         r.ui.setconfig('ui', 'nontty', 'true', 'hgweb')
         r.baseui.setconfig('ui', 'nontty', 'true', 'hgweb')
+        # displaying bundling progress bar while serving feel wrong and may
+        # break some wsgi implementation.
+        r.ui.setconfig('progress', 'disable', 'true', 'hgweb')
+        r.baseui.setconfig('progress', 'disable', 'true', 'hgweb')
         self.repo = r
         hook.redirect(True)
         self.repostate = ((-1, -1), (-1, -1))