Import feature misidentifies root path for endpoint

[dkharlan]

Given thing_doer.yml:

tags:
  - "thing_doer"
summary: "Do a thing"
description: ""
consumes:
  - "application/json"
produces:
  - "application/json"
parameters:
  - in: "body"
    name: "body"
    required: true
    schema:
      import: "models/stuff.yml"
responses:
  200:
    description: "The results of doing a thing"
    schema:
      type: "object"
      properties:
        whatever:
          type: "integer"

with a file structure as follows:

specs/
   thing_doer.yml
   models/
      stuff.yml

I get the following exception:

[2017-05-17 16:08:43,303] ERROR in app: Exception on /apispec_1.json [GET]
Traceback (most recent call last):
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flasgger/utils.py", line 294, in load_from_file
    with open(swag_path) as yaml_file:
FileNotFoundError: [Errno 2] No such file or directory: 'models/raw_text.yml'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flask/app.py", line 1982, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flask/app.py", line 1614, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flask/app.py", line 1517, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flask/app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flask/app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flask/views.py", line 84, in view
    return self.dispatch_request(*args, **kwargs)
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flask/views.py", line 149, in dispatch_request
    return meth(*args, **kwargs)
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flasgger/base.py", line 229, in get
    endpoint=rule.endpoint, verb=verb
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flasgger/utils.py", line 338, in parse_docstring
    full_doc = parse_imports(full_doc, root_path)
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flasgger/utils.py", line 420, in parse_imports
    imported_doc = load_from_file(filepath, root_path=root_path)
  File "/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flasgger/utils.py", line 301, in load_from_file
    with open(swag_path) as yaml_file:
FileNotFoundError: [Errno 2] No such file or directory: '/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flasgger/models/raw_text.yml'

The culprit appears to be https://github.com/rochacbruno/flasgger/blob/master/flasgger/utils.py#L362 where obj.__globals__['__file__'] resolves to '/Users/dkharlan/venvs/myenv/lib/python3.6/site-packages/flasgger/utils.py'. I'm not really sure why this would happen (maybe the way the endpoint function is imported influences the value of __file__? I'm unclear on Python's semantics here).

Thank you -- please let me know if you need more details.