nginx sent gzipped responses to clients those do not support gzip,
if "gzip_static on" and "gzip_vary off"; the bug had been introduced in r3250

server name related merges:

*) If .domain.com, .sub.domain.com, and .domain-some.com were defined,
   then .sub.domain.com was matched by .domain.com: wildcard names hash
   was built incorrectly due to sorting order issue of "." vs "-".
   They were sorted as
       com.domain  com.domain-some  com.domain.sub
   while they should be sorted as
       com.domain  com.domain.sub   com.domain-some
   for correct hash building

*) test space between "~" and regex in server_name and invalid_referers

*) do not run regex for empty host name since regex always fails in this case,
   the bug had been introduced in r2196

fix building by gcc45

WebDAV fixes:

*) check unsafe Destination
*) omit '\0' from "Location" header on MKCOL request

gzip related fixes:

*) do not disable gzip for MSIE 6.0 SV1 in "gzip_disable msie6"
*) nginx always sent "Vary: Accept-Encoding",
   if both gzip_static and gzip_vary were on

allow cross device temporary files atomic copying

various header fixes:

*) allow to proxy_pass_header/fastcgi_pass_header "X-Accel-Redirect",
   "X-Accel-Limit-Rate", "X-Accel-Buffering", and "X-Accel-Charset"
*) fix handling "Last-Modified" and "Accept-Ranges" for upstream responses
*) clear "Accept-Ranges" for SSI responses

fix variuos segfaults:

*) fix segfault if 400 or 414 errors are handled intricately
*) ngx_http_upstream_create() to cleanup the previous upstream after
   internal redirect

various image filter fixes and features:

*) variables support in image_filter
*) fix transparency in GIF
*) fix alpha-channel transparency in PNG
*) image_filter_transparency