basic-test.sh: explicitly check for uncompressed objects
basic-test.sh: explicitly check for uncompressed objects

It's not enough to check that the dir exists, since that's done by
default when we open the repo. We want to actually check that
uncompressed objects were cached (i.e. the opposite of the earlier error
path).

Closes: #903
Approved by: cgwalters

GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree