iotests: Rework 113

This test case has been broken since 398e6ad014df261d (roughly half a
year). qemu-img amend requires its output image to be R/W, so it opens
it as such; the node is then turned into an read-only node automatically
which is now accompanied by a warning, however. This warning has not
been part of the reference output.

For one thing, this warning shows that we cannot keep the test case as
it is. We would need a format that has no create_opts but that does
have write support -- we do not have such a format, though.

Another thing is that qemu now actually checks whether an image format
supports amendment instead of whether it has create_opts (since the
former always implies the latter). So we can now use any format that
does not support amendment (even if it supports creation) and thus test
the same code path.

The reason nobody has noticed the breakage until now of course is the
fact that nobody runs the iotests for nbd+bochs. There actually was
never any reason to set the protocol to "nbd" but because that was
technically correct; functionally it made no difference. So that is the
first thing we are going to change: Make the protocol "file" instead so
that people might actually notice breakage here.

Secondly, now that bochs no longer works for the amend test case, we
have to change the format there anyway. Set let us just bend the truth
a bit, declare this test a raw test. In fact, that does not even
concern the bochs test cases, other than the output now reading 'bochs'
instead of 'IMGFMT'.

So with this test now being a raw test, we can rework the amend test
case to use raw instead.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20180509210023.20283-8-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>