Double encoding of query parameters

Problem/Motivation

If you add query parameters e.g. search api facet parameters to the redirect the second save of the redirect will lead to double encoded parameters.
Example:

• Initial Input: ausflugstipps?f[0]=field_offer_types:266&f[1]=field_geo_location%253Afield_regions:9
• First save: ausflugstipps?f%5B0%5D=field_offer_types%3A266&f%5B1%5D=field_geo_location%3Afield_regions%3A9
• Second save: ausflugstipps?f%255B0%255D=field_offer_types%253A266&f%255B1%255D=field_geo_location%253Afield_regions%253A9

Proposed resolution

Run an urldecode() when saving the query parameters.
I propose to do this in _redirect_extract_url_options() - this is the central place where the data that are to be saved are processed.

This change should be safe since the query parameters are passed as options to url() - see redirect_redirect(). url() itself calls drupal_http_build_query() which then runs an rawurlencode() on every key & value of the query.

Remaining tasks

Reviews needed.

User interface changes

None.

API changes

Stored values might change. If other modules implement the alter hooks this could lead to unmet expectations.

Data model changes

None.