In comments from https://review.openstack.org/8798 it was raised that it
might make sense to forbid some substrings in the name_filter
middleware.
There is now a new forbidden_regexp option for the name_filter
middleware to specify which substrings to forbid. The default is
"/\./|/\.\./|/\.$|/\.\.$" (or in a non-regexp language: the /./ and /../
substrings as well as strings ending with /. or /..).
This can be useful for extra paranoia to avoid directory traversals
(bug 1005908), or for more general filtering.
Change-Id: I39bf2de45b9dc7d3ca4d350d24b3f2276e958a62
DocImpact: new forbidden_regexp option for the name_filter middleware
faff4ae769