2.5.20 incomplete HTTP http headers sent for cached files

[PiotrC]

Dear All,
Sorry for double post. but previously I have posted it in wrong section - develpoment one.
I have met following problem with my Joomla 2.5.20 with gzipping enabled:
When I disable System - Cache plugin I got http header response:

Code: Select all

...
Content-Type: text/html; charset-utf8
...

Http header is controlled by Joomla then.
After enabling System - Cache plugin my headers change a little bit:

Code: Select all

...
ETag: xxxxxxxxxxxxxxxxxxx
...
Content-Type: text/html
...

So one of headers (Content-Type) is no more (correctly) controlled by Joomla.

Regards,
Piotr