Fixed #21389 -- Accept most valid language codes

By removing the 'supported' keyword from the detection methods and only relying
on a cached settings.LANGUAGES, the speed of said methods has been improved;
around 4x raw performance. This allows us to stop checking Python's incomplete
list of locales, and rely on a less restrictive regular expression for
accepting certain locales.

HTTP Accept-Language is defined as being case-insensitive, based on this fact
extra performance improvements have been made; it wouldn't make sense to
check for case differences.

1 files changed, 8 insertions, 0 deletions

diff --git a/docs/releases/1.7.txt b/docs/releases/1.7.txt
index 4d12a58e72..aef8842e36 100644
--- a/docs/releases/1.7.txt
+++ b/docs/releases/1.7.txt
@@ -1125,6 +1125,14 @@ Miscellaneous
   For example, if you use multi-inheritance, you need to define custom primary
   key fields on parent models, otherwise the default ``id`` fields will clash.
 
+* :meth:`~django.utils.translation.parse_accept_lang_header` now returns
+  lowercase locales, instead of the case as it was provided. As locales should
+  be treated case-insensitive this allows us to speed up locale detection.
+
+* :meth:`~django.utils.translation.get_language_from_path` and
+  :meth:`~django.utils.translation.trans_real.get_supported_language_variant`
+  now no longer have a ``supported`` argument.
+
 .. _deprecated-features-1.7:
 
 Features deprecated in 1.7