code: def _get_dependencies_from_pip(ireq, sources):
      
      extras = ireq.extras or ()
      try:
          wheel = build_wheel(ireq, sources)
      except WheelBuildError:
          # XXX: This depends on a side effect of `build_wheel`. This block is
          # reached when it fails to build an sdist, where the sdist would have
          # been downloaded, extracted into `ireq.source_dir`, and partially
          # built (hopefully containing .egg-info).
          metadata = read_sdist_metadata(ireq)
          if not metadata:
              raise
      else:
          metadata = wheel.metadata
      requirements = _read_requirements(metadata, extras)
      requires_python = _read_requires_python(metadata)
      return requirements, requires_python
docs: Retrieves dependencies for the requirement from pipenv.patched.notpip internals.
  
      The current strategy is to try the followings in order, returning the
      first successful result.
  
      1. Try to build a wheel out of the ireq, and read metadata out of it.
      2. Read metadata out of the egg-info directory if it is present.