In some systems[1], the gvfs-gphoto2-volume-monitor is not
the only GVFS monitor that could be hogging the device.

[1] In particular in my Ubuntu 14.04.x LTS, this is the result
of a `ps aux | grep gvfs`:
knocte1+  2150  0.0  0.0 196640  3204 ?        Sl   jun25   0:00 /usr/lib/gvfs/gvfsd
knocte1+  2157  0.0  0.0 345660  3124 ?        Sl   jun25   0:00 /usr/lib/gvfs/gvfsd-fuse /run/user/1000/gvfs -f -o big_writes
knocte1+  2403  0.0  0.0 298964  5552 ?        Sl   jun25   0:00 /usr/lib/gvfs/gvfs-udisks2-volume-monitor
knocte1+  2423  0.0  0.0 285964  3376 ?        Sl   jun25   0:00 /usr/lib/gvfs/gvfs-afc-volume-monitor
knocte1+  2428  0.0  0.0 212440  3456 ?        Sl   jun25   0:00 /usr/lib/gvfs/gvfs-gphoto2-volume-monitor
knocte1+  2433  0.0  0.0 204936  3492 ?        Sl   jun25   0:00 /usr/lib/gvfs/gvfs-mtp-volume-monitor
knocte1+  2451  0.0  0.0 433144  3636 ?        Sl   jun25   0:00 /usr/lib/gvfs/gvfsd-trash --spawner :1.5 /org/gtk/gvfs/exec_spaw/1
knocte1+  2469  0.0  0.0 124728  3036 ?        Sl   jun25   0:00 /usr/lib/gvfs/gvfsd-metadata
knocte1+  2479  0.0  0.0 270376  3084 ?        Sl   jun25   0:00 /usr/lib/gvfs/gvfsd-burn --spawner :1.5 /org/gtk/gvfs/exec_spaw/3
knocte1+  8648  0.0  0.0 296744  4760 ?        Sl   15:11   0:00 /usr/lib/gvfs/gvfsd-http --spawner :1.5 /org/gtk/gvfs/exec_spaw/4