cwltool does not recognize equivalent types

`../types/singletype.yml`
```
name: simple_record
type: record
fields:
prop: string
```

`../tools/clt2.cwl`
```
#!/usr/bin/env cwl-runner

# Inline schemadef

class: CommandLineTool
cwlVersion: v1.0

requirements:
SchemaDefRequirement:
types:
- name: user_type1
type: record
fields:
- name: prop
type: string

inputs:
in1: user_type1

outputs:
out1:
type: user_type1
outputBinding:
outputEval: $(inputs.in1)

baseCommand: []
arguments: []
```

`../workflows/wf1.cwl`
```
class: Workflow
cwlVersion: v1.0
inputs:
in1: ../types/singletype.yml#simple_record

steps:
s1:
run: ../tools/clt2.cwl
in:
in1: in1
out: [out1]

outputs:
out1:
type: user_type1
outputSource: s1/out1

requirements:
SchemaDefRequirement:
types:
- $import: ../types/singletype.yml
- name: user_type1
type: record
fields:
- name: prop
type: string
```

`cwltool --validate` claims all of these are different types, when in fact they are identical.