I noticed that while we have tests to make sure that people don't
specify a Dockerfile (via -f) that's outside of the build context
when using the docker cli, we don't check on the server side to make
sure that API users have the same check done. This would be a security
risk.
While in there I had to add a new util func for the tests to allow us to
send content to the server that isn't json encoded - in this case a tarball
Signed-off-by: Doug Davis <dug@us.ibm.com>
Upstream-commit: 198ff76de59a600ce900497fd4a6131ee4448c48
Component: engine