bug: language cookie not set

[MathJoDE]

• Gitea version (or commit ref): 1.14.0+dev-615-gb2c20b68a
• issue encountered on try.gitea.io
  Can you reproduce this issue at try.gitea.io?
  • Yes (provide example URL) just choose any random page at https://try.gitea.io (and clear your cookies before)

Description

The lang cookie is not set at all.
This leads to the language always being the default, and the language changer at the bottom does not work at all (except for reloading the page).

However, the language cookie is loaded. (If you have the cookie stored from some past session and change it's value manually, the language changes as expected.)

[MathJoDE]

Addition: at least in version 1.13.1 this bug did not exist.