Fix request #6406: Upgrade to 6.11 on Centos 6 block git web access

Change-Id: I7ebe5c4380c4ef2bb399ab62ae98a045ab738a54
Merge commit 'refs/changes/86/2086/2' of ssh://gerrit.tuleap.net:29418/tuleap into stable

* ssh://gerrit.tuleap.net:29418/tuleap:
  Fix request #6406: Upgrade to 6.11 on Centos 6 block git web access

Change-Id: I9496fe0c64bcc0b8b8ebbd818642acf338b97355
This is Tuleap 6.11.99.18

Change-Id: I9ac16af75c987684c1f2739a60232ffd9a40ba48