Redirect after submission gives error on Chrome & Firefox

[tricksel]

Version 4.3.0 gives a problem after submission of a form on Chrome and Firefox. Safari works OK. Chrome gives me "ERR_RESPONSE_HEADERS_MULTIPLE_LOCATION". Version 4.2.7 is OK. This happens both on Bolt 3.7.1 and Bolt 3.6.11.

[ghispi]

Seems to be related to #283 & #284