Fix opening PR from fork

sweagent/environment/swe_env.py

@@ -25,6 +25,7 @@
     get_container,
     get_gh_issue_data,
     get_instances,
+    parse_gh_issue_url,
     read_with_timeout,
     LOGGER_NAME,
 )
@@ -802,11 +803,27 @@ def open_pr(self, *, trajectory, _dry_run: bool=False):
             error_msg="Failed to commit changes",
             timeout_duration=10,
         )
-        # If users want to push to a fork, we add a new remote and push to that
-        # otherwise, we push to 'origin' which has already been set up
+
+        owner, repo, _ = parse_gh_issue_url(issue_url)
+        # If `--repo_path` was specified with a different github URL, then the record will contain
+        # the forking user
+        assert self.record is not None
+        forker, _ = self.record["repo"].split("/")
+        head = branch_name
         remote = "origin"
-        assert self.record is not None  # mypy
-        owner, repo = self.record["repo"].split("/")
+        if forker != owner:
+            head = f"{forker}:{branch_name}"
+            token_prefix = ""
+            if self._github_token:
+                token_prefix = f"{self._github_token}@"
+            fork_url = f"https://{token_prefix}github.com/{forker}/{repo}.git"
+            logger.debug(f"Using fork: {fork_url}")
+            self.communicate_with_handling(
+                input=f"git remote add fork {fork_url}",
+                error_msg="Failed to create new git remote",
+                timeout_duration=10,
+            )
+            remote = "fork"
         dry_run_prefix = "echo " if _dry_run else ""
         self.communicate_with_handling(
             input=f"{dry_run_prefix} git push {remote} {branch_name}",
@@ -816,8 +833,6 @@ def open_pr(self, *, trajectory, _dry_run: bool=False):
             ),
             timeout_duration=10,
         )
-
-        # todo: add representation of trajectory to PR body
         body =  (
             f"This is a PR opened by AI tool [SWE Agent](https://github.com/princeton-nlp/SWE-agent/) " 
             f"to close [#{issue.number}]({issue_url}) ({issue.title}).\n\nCloses #{issue.number}."
@@ -829,7 +844,7 @@ def open_pr(self, *, trajectory, _dry_run: bool=False):
                 owner=owner,
                 repo=repo,
                 title=f"SWE-agent[bot] PR to fix: {issue.title}",
-                head=branch_name,
+                head=head,
                 base="main",
                 body=body,
                 draft=True,
@@ -838,4 +853,4 @@ def open_pr(self, *, trajectory, _dry_run: bool=False):
                 f"🎉 PR created as a draft at {pr_info.html_url}. Please review it carefully, push "
                 "any required changes onto the branch and then click "
                 "'Ready for Review' to bring it to the attention of the maintainers."
-            )
+            )