I've patched ntfs-3g to symlink mount.ntfs to mount.ntfs-3g and it works
as expected.  If the new ntfs-3g is installed as a system package, that
is to say.

Indeed, libmount seems to only look in

	/run/current-system/profile/sbin/mount.*

and not in

	~/.guix-profile/sbin/mount.*.

Is this the behaviour we really want?  Maybe, considering libmount is fairly
low level.  Any insights?

To see that you can try the following command:

--8<---------------cut here---------------start------------->8---
> sudo LIBMOUNT_DEBUG=all mount /dev/sda1 /mnt
5132: libmount:     INIT: library debug mask: 0xffff
[...]
5132: libmount:      CXT: [0x2162690]: /run/current-system/profile/sbin/mount.ntfs ... not found
[...]
--8<---------------cut here---------------end--------------->8---

See https://github.com/storaged-project/udisks/issues/532 for more
details.

I'll submit a patch soon.

--
Pierre Neidhardt