problem building branch 3.6.x

Hello

I have to work on a 3.6.x problem that doesn't appear in the master
branch.

I can build the master branch just fine with :
git clean -dfx
git pull
export PYTHON=python2
install_dir="/home/myuser/libreoffice/$1"
./autogen.sh --prefix="$install_dir/usr" \
 --exec-prefix="$install_dir/usr" --sysconfdir="$install_dir/etc" \
 --libdir="$install_dir/usr/lib" --mandir="$install_dir/usr/share/man" \
 --enable-debug --enable-dbgutil \
 --without-doxygen --disable-zenity
make

I use archlinux.

If I checkout to a 3.6 branch the build fail with :
#####################################
…
  internal build errors:

ERROR: error 512 occurred while
making /home/max/libreoffice/3_6/dictionaries/prj

 it seems that the error is inside 'dictionaries', please re-run build
 inside this module to isolate the error and/or test your fix:

build_error.log should contain the captured output of the failed
module(s)

-----------------------------------------------------------------------
To rebuild a specific module:

make dictionaries.clean # optional
make dictionaries
…
#####################################

If I execute :
make dictionaries.clean
make dictionaries

It fail with :
#####################################
=============
(1/1) Building module dictionaries
=============
Entering /home/max/libreoffice/3_6/dictionaries/prj

-----------------------------------------------
force_dmake_to_error
Error: No makefile.mk found!
-----------------------------------------------
dmake:  Error executing 'force_dmake_to_error': No such file or
directory
dmake:  Error code -1, while making 'no_traget'

-----------------------------------------------------------------------
        Oh dear - something failed during the build - sorry !
  For more help with debugging build errors, please see the section in:
            http://wiki.documentfoundation.org/Development

  internal build errors:

ERROR: error 65280 occurred while
making /home/max/libreoffice/3_6/dictionaries/prj

 it seems that the error is inside 'dictionaries', please re-run build
 inside this module to isolate the error and/or test your fix:

build_error.log should contain the captured output of the failed
module(s)
#####################################

Can you help me please ?

Thank you in advance.

-- 
Maxime de Roucy
Groupe LINAGORA - OSSA
80 rue Roque de Fillol
92800 PUTEAUX
Tel. : 0033(0)642004909