mod_perl2: 304 (not modified) and custom headers

1. Problem Description:

It seems, that if I set status to 304, all custom headers being ignored and
not sent to to the client.
I'm making cross-domain ajax script and it should pass
Access-Control-Allow-Origin even on 304 response.
Works fine if data been modified but 304 response has no my headers.

2. Used Components and their Configuration:

*** mod_perl version 2.000008

*** using /usr/local/lib/perl5/site_perl/5.20/mach/Apache2/BuildConfig.pm

*** Makefile.PL options:
  MP_APR_CONFIG  => /usr/local/bin/apr-1-config
  MP_APR_LIB     => aprext
  MP_APXS        => /usr/local/sbin/apxs
  MP_COMPAT_1X   => 1
  MP_GENERATE_XS => 1
  MP_LIBNAME     => mod_perl
  MP_USE_DSO     => 1


*** The httpd binary was not found


*** (apr|apu)-config linking info

 -L/usr/local/lib -laprutil-1  -ldb-5.3 -lgdbm  -lexpat -liconv -L/usr/lib
-L/usr/local/lib -L/usr/local/lib/db5
 -L/usr/local/lib -lapr-1 -lcrypt  -lpthread



*** /usr/local/bin/perl -V
Summary of my perl5 (revision 5 version 20 subversion 1) configuration:

  Platform:
    osname=freebsd, osvers=9.3-release-p4,
archname=amd64-freebsd-thread-multi
    uname='freebsd storage.cobweb-software.com 9.3-release-p4 freebsd
9.3-release-p4 #0 r273928: sat nov 1 17:16:18 msk 2014
[email protected]:usrobjusrsrcsysgeneric amd64 '
    config_args='-sde -Dprefix=/usr/local
-Darchlib=/usr/local/lib/perl5/5.20/mach
-Dprivlib=/usr/local/lib/perl5/5.20
-Dman3dir=/usr/local/lib/perl5/5.20/perl/man/man3
-Dman1dir=/usr/local/man/man1
-Dsitearch=/usr/local/lib/perl5/site_perl/5.20/mach
-Dsitelib=/usr/local/lib/perl5/site_perl/5.20 -Dscriptdir=/usr/local/bin
-Dsiteman3dir=/usr/local/lib/perl5/5.20/man/man3
-Dsiteman1dir=/usr/local/man/man1 -Ui_malloc -Ui_iconv -Uinstallusrbinperl
-Dcc=cc -Duseshrplib -Dinc_version_list=none
-Dccflags=-DAPPLLIB_EXP="/usr/local/lib/perl5/5.20/BSDPAN" -Doptimize=-g
-DDEBUGGING -Ui_gdbm -Dusemultiplicity=y -Duse64bitint -Dusethreads=y
-Dusemymalloc=n'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-DAPPLLIB_EXP="/usr/local/lib/perl5/5.20/BSDPAN"
-DHAS_FPSETMASK -DHAS_FLOATINGPOINT_H -DDEBUGGING -fno-strict-aliasing
-pipe -fstack-protector -I/usr/local/include',
    optimize='-g',
    cppflags='-DAPPLLIB_EXP="/usr/local/lib/perl5/5.20/BSDPAN"
-DHAS_FPSETMASK -DHAS_FLOATINGPOINT_H -DDEBUGGING -fno-strict-aliasing
-pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.2.1 20070831 patched [FreeBSD]',
gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags ='-pthread -Wl,-E  -fstack-protector -L/usr/local/lib'
    libpth=/usr/lib /usr/local/lib /usr/include/gcc/4.2 /usr/lib
    libs=-lgdbm -lm -lcrypt -lutil
    perllibs=-lm -lcrypt -lutil
    libc=, so=so, useshrplib=true, libperl=libperl.so
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='
 -Wl,-R/usr/local/lib/perl5/5.20/mach/CORE'
    cccdlflags='-DPIC -fPIC', lddlflags='-shared  -L/usr/local/lib
-fstack-protector'


Characteristics of this binary (from libperl):
  Compile-time options: DEBUGGING HAS_TIMES MULTIPLICITY PERLIO_LAYERS
                        PERL_DONT_CREATE_GVSV
                        PERL_HASH_FUNC_ONE_AT_A_TIME_HARD
                        PERL_IMPLICIT_CONTEXT PERL_MALLOC_WRAP
                        PERL_NEW_COPY_ON_WRITE PERL_PRESERVE_IVUV
                        PERL_TRACK_MEMPOOL USE_64_BIT_ALL USE_64_BIT_INT
                        USE_ITHREADS USE_LARGE_FILES USE_LOCALE
                        USE_LOCALE_COLLATE USE_LOCALE_CTYPE
                        USE_LOCALE_NUMERIC USE_PERLIO USE_PERL_ATOF
                        USE_REENTRANT_API
  Built under freebsd
  Compiled at Nov  9 2014 08:27:44
  %ENV:
    PERL5LIB="/raid/www/lib"
    PERL_LWP_USE_HTTP_10="1"
  @INC:
    /raid/www/lib
    /usr/local/lib/perl5/5.20/BSDPAN
    /usr/local/lib/perl5/site_perl/5.20/mach
    /usr/local/lib/perl5/site_perl/5.20
    /usr/local/lib/perl5/5.20/mach
    /usr/local/lib/perl5/5.20
    .

*** Packages of interest status:

Apache2            : -
Apache2::Request   : -
CGI                : 3.65
ExtUtils::MakeMaker: 6.98, 6.98
LWP                : 6.08
mod_perl           : -
mod_perl2          : 2.000008


3. This is the core dump trace: (if you get a core dump):

  [CORE TRACE COMES HERE]

This report was generated by /usr/local/bin/mp2bug on Wed Nov 12 09:51:30
2014 GMT.