feat: support agit prs in pr detection

src/prs.rs

@@ -1601,17 +1601,27 @@ async fn guess_pr(
     let head = local_repo.head()?;
     eyre::ensure!(head.is_branch(), "head is not on branch");
     let local_branch = git2::Branch::wrap(head);
-    let remote_branch = local_branch.upstream()?;
-    let remote_head_name = remote_branch
-        .get()
-        .name()
-        .ok_or_eyre("remote branch does not have valid name")?;
+    let local_branch_name = local_branch.name()?.ok_or_eyre("branch name is not utf8")?;
+    let config = local_repo.config()?;
+    let remote_head_name = config.get_string(&format!("branch.{local_branch_name}.merge"))?;
+
+    let maybe_agit = remote_head_name.strip_prefix("refs/for/").and_then(|s| s.split_once("/"));
+
+    match maybe_agit {
+        Some((base, head)) => {
+            let username = api.user_get_current().await?.login.ok_or_eyre("user does not have username")?.to_lowercase();
+            let head = format!("{username}/{head}");
+            return Ok(api.repo_get_pull_request_by_base_head(repo.owner(), repo.name(), base, &head).await?);
+        }
+        None => {
             let remote_head_short = remote_head_name
                 .rsplit_once("/")
                 .map(|(_, b)| b)
-        .unwrap_or(remote_head_name);
+                .unwrap_or(&remote_head_name);
+
             let this_repo = api.repo_get(repo.owner(), repo.name()).await?;
 
+
             // check for PRs on the main branch first
             let base = this_repo
                 .default_branch
@@ -1664,6 +1674,8 @@ async fn guess_pr(
                     return Ok(pr);
                 }
             }
+        }
+    }
 
     eyre::bail!("could not find PR");
 }