bc4590fd7d
the `convertVolumeToMount()` function did not take
anonymous volumes into account when converting
volume specifications to bind-mounts.
this resulted in the conversion to try to
look up an empty "source" volume, which
lead to an error;
undefined volume:
this patch distinguishes "anonymous"
volumes from bind-mounts and named-volumes,
and skips further processing if no source
is defined (i.e. the volume is "anonymous").
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>