Fix push_target remote reuse and non-fatal per-repo errors

- git_mirror: reuse existing push_target remote via remote_set_url
  instead of failing on 'remote already exists' on subsequent cycles
- mirror_cycle: catch per-repo errors instead of propagating with ?
  so one failed clone doesn't abort the remaining 87 repos
- Add PLAN.md with bug tracking checklist

1 files changed, 12 insertions, 1 deletions

diff --git a/src/git_mirror.rs b/src/git_mirror.rs
index 47c0442..6866de3 100644
--- a/src/git_mirror.rs
+++ b/src/git_mirror.rs
@@ -134,7 +134,18 @@ impl GitMirror {
         let repo = git2::Repository::open(repo_path)
             .with_context(|| format!("failed to open bare repo at {:?}", repo_path))?;
 
-        let mut remote = repo.remote("push_target", target_url)?;
+        let remote_name = "push_target";
+
+        match repo.find_remote(remote_name) {
+            Ok(_) => {
+                repo.remote_set_url(remote_name, target_url)?;
+            }
+            Err(_) => {
+                repo.remote(remote_name, target_url)?;
+            }
+        }
+
+        let mut remote = repo.find_remote(remote_name)?;
 
         let mut callbacks = RemoteCallbacks::new();
         callbacks.credentials(|_url, _username, _allowed| git2::Cred::default());