Weird lib error with a jhbuild-built epiphany+webkit2

Hi,

I see a weird thing when I try to launch epiphany after a fresh build
with jhbuild:

$ jhbuild run /opt/gnome/bin/epiphany
ephy-profile-migrator: error while loading shared libraries:
libwebkit2gtk-3.0.so.18: cannot open shared object file: No such file
or directory
Failed to run the migrator process, Web will now abort.

But the lib is there and seen in the jhbuild environment:

$ ls -l /opt/gnome/lib64/libwebkit2gtk-3.0.so.18
lrwxrwxrwx 1 nimai users 27 20 sep 03:55
/opt/gnome/lib64/libwebkit2gtk-3.0.so.18 ->
libwebkit2gtk-3.0.so.18.0.2
$ ls -l /opt/gnome/lib64/libwebkit2gtk-3.0.so.18.0.2
-rwxr-xr-x 1 nimai users 34M 20 sep 03:55
/opt/gnome/lib64/libwebkit2gtk-3.0.so.18.0.2

$ file /opt/gnome/lib64/libwebkit2gtk-3.0.so.18.0.2
/opt/gnome/lib64/libwebkit2gtk-3.0.so.18.0.2: ELF 64-bit LSB shared
object, x86-64, version 1 (GNU/Linux), dynamically linked,
BuildID[sha1]=0xc67843116472340e2b01ace0d7b4f221e2d9fe9b, not stripped

$ jhbuild run ldd /opt/gnome/bin/ephy-profile-migrator /opt/gnome/bin/epiphany
/opt/gnome/bin/ephy-profile-migrator:
	linux-vdso.so.1 (0x00007fffd28e3000)
	libgmodule-2.0.so.0 => /opt/gnome/lib64/libgmodule-2.0.so.0
(0x00007f7fed16b000)
	libgthread-2.0.so.0 => /opt/gnome/lib64/libgthread-2.0.so.0
(0x00007f7fecf6a000)
	librt.so.1 => /usr/lib/librt.so.1 (0x00007f7fecd2e000)
	libX11.so.6 => /usr/lib/libX11.so.6 (0x00007f7fec9f5000)
	libxslt.so.1 => /usr/lib/libxslt.so.1 (0x00007f7fec7b8000)
	libz.so.1 => /usr/lib/libz.so.1 (0x00007f7fec5a2000)
	libm.so.6 => /usr/lib/libm.so.6 (0x00007f7fec2a7000)
	libxml2.so.2 => /usr/lib/libxml2.so.2 (0x00007f7febf4b000)
	libwebkit2gtk-3.0.so.18 => /opt/gnome/lib64/libwebkit2gtk-3.0.so.18
(0x00007f7fea3b1000)
	[..]
/opt/gnome/bin/epiphany:
	linux-vdso.so.1 (0x00007ffffbd40000)
	libgmodule-2.0.so.0 => /opt/gnome/lib64/libgmodule-2.0.so.0
(0x00007fcd1064b000)
	[..]
	libwebkit2gtk-3.0.so.18 => /opt/gnome/lib64/libwebkit2gtk-3.0.so.18
(0x00007fcd0d891000)

I've had that kind of problem once when a lib was compiled in 32bits
instead of 64bits but it's obviously not the same issue here.
I can't understand what could be the problem.

Someone happens to have an idea on this?
Thank you!

Here are some extras info which might (or not) be useful:
From .jhbuildrc:
[..]
prefix = '/opt/gnome'
os.environ['CFLAGS'] = '-Wall -g -O0'
autogenargs='--disable-gtk-doc --disable-documentation ' + \
            '--disable-docs'
module_autogenargs['epiphany']='--with-webkit2'

$ uname -rmo
3.5.3-1-ARCH x86_64 GNU/Linux

-- 
nimai