Make a helper function for adding requirements

This is for reuse in the declarative requires patch.

pip/req/req_set.py

@@ -498,6 +498,17 @@ def _prepare_file(self, finder, req_to_install):
  # ###################### #
  dist = abstract_dist.dist(finder)
  more_reqs = []
+ def add_req(subreq):
+ if self.has_requirement(subreq.project_name):
+ # FIXME: check for conflict
+ return
+ subreq = InstallRequirement(
+ str(subreq),
+ req_to_install,
+ isolated=self.isolated,
+ )
+ more_reqs.append(subreq)
+ self.add_requirement(subreq)
 
  # We add req_to_install before its dependencies, so that when
  # to_install is calculated, which reverses the order,
@@ -525,16 +536,7 @@ def _prepare_file(self, finder, req_to_install):
  set(dist.extras) & set(req_to_install.extras)
  )
  for subreq in dist.requires(available_requested):
- if self.has_requirement(subreq.project_name):
- # FIXME: check for conflict
- continue
- subreq = InstallRequirement(
- str(subreq),
- req_to_install,
- isolated=self.isolated,
- )
- more_reqs.append(subreq)
- self.add_requirement(subreq)
+ add_req(subreq)
 
  # cleanup tmp src
  self.reqs_to_cleanup.append(req_to_install)