corrupt files via /run/user/<id>/gvfs

[j^]

files can be corrupt if copied from /run/user/<id>/gvfs/

this happens for files around 8-10k in size.
the resulting file is truncated.

the following fails:

cp "/run/user/1000/gvfs/mtp:host=%5Busb%3A001%2C018%5D/Internal storage/test.json" /tmp/failed.json

this works:

gio copy mtp://[usb:001,018]/Internal%20storage/test.json /tmp/ok.json

upstream bug: https://bugzilla.gnome.org/show_bug.cgi?id=793121