gimp 2.6.12 not compiling with gegl 0.2.0 (Bug #379)

gegl 0.2.0 has been pushed into test grimoire at the beginning of the month. But gimp can't compile against it :

Found source file /var/spool/sorcery/gimp-2.6.12.tar.bz2 for spell gimp in /var/spool/sorcery
Waiting for any Solo casts to complete...
Waiting for any other casts of gimp to complete... done.
Staging enabled
castfs: checking sanity of <mnt-dir> and <stage-dir>
castfs: stagedir is okay!
Preparing gimp
Hash checking source file gimp-2.6.12.tar.bz2...
Algorithm used: sha512
Allowing new hash sha512
Checking spell level WORKS_FOR_ME
Spell level is a new allowed level
Hash verification succeeded
Unpacking source file gimp-2.6.12.tar.bz2 for spell gimp.
patching file plug-ins/file-uri/uri-backend-libcurl.c
Building gimp
Building in dir: /usr/src/gimp-2.6.12
gimp 2.6.12

checking for a BSD-compatible install... /bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking for gcc... gcc
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
checking for suffix of executables...
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
[...]
checking for xgettext... (cached) /usr/bin/xgettext
checking for iso-codes... yes
checking for BABL... yes
checking for GEGL... no
configure: error: Package requirements (gegl >= 0.0.18) were not met:

No package 'gegl' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables GEGL_CFLAGS
and GEGL_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.