Expander: when expanding with SkipSchema, the relative path is lost #182
Description
When running ExpandSpec with the SkipSchema option, for $ref's in parameters or responses, relative paths when exploring
multiple documents pointed by $ref is not properly maintained.
This happens when a ref-ed document in a folder refers to another doc via relative paths like "../folder".
In the attached example, the "working" spec SHOULD not work whereas the "not-working" spec SHOULD.
The "SkipSchema" option is used by the spec flattening feature exposed by go-openapi/analysis.
Original issue: go-swagger/go-swagger#2743
cc: @mateusbandeiraa