-o requires prefix for some reason

[nirroz93]

Works fine without -o
openapi2jsonschema --expanded --kubernetes --stand-alone --strict "https://raw.githubusercontent.com/kubernetes/kubernetes/v1.19.2/api/openapi-spec/swagger.json"
but with -o
openapi2jsonschema --expanded --kubernetes --stand-alone --strict "https://raw.githubusercontent.com/kubernetes/kubernetes/v1.19.2/api/openapi-spec/swagger.json" -o /tmp/v1.19.2-standalone-strict
has many errors with the format

An error occured processing validatingwebhookconfigurationlist: URLError: <urlopen error [Errno 2] No such file or directory: '/tmp/tmp/v1.19.2-standalone-strict/_definitions.json'>

[jcmcken]

I see this issue whenever --stand-alone and --expanded are used together, regardless if -o is used.