gerris: Allow partial upstream failures

Author: powerboat9

src/git.rs

@@ -14,7 +14,7 @@ mod rev_list;
 mod switch;
 
 pub use branch::{branch, StartingPoint};
-pub use cherry_pick::cherry_pick;
+pub use cherry_pick::{cherry_pick, cherry_pick_abort};
 pub use commit::commit;
 pub use fetch::fetch;
 pub use log::log;

src/git/cherry_pick.rs

@@ -18,3 +18,16 @@ impl GitCmd for CherryPick {
         cmd.arg("cherry-pick").arg(self.commit);
     }
 }
+
+#[derive(Default)]
+pub struct CherryPickAbort;
+
+pub fn cherry_pick_abort() -> CherryPickAbort {
+    CherryPickAbort
+}
+
+impl GitCmd for CherryPickAbort {
+    fn setup(self, cmd: &mut Command) {
+        cmd.arg("cherry-pick").arg("--abort");
+    }
+}

src/upstream.rs

@@ -224,12 +224,30 @@ pub async fn prepare_commits(
 
     info!("created branch `{new_branch}`");
 
-    rev_list.lines().try_for_each(|commit| {
+    // cherry-pick until we hit a commit we can't apply
+    // if we hit such a commit, only error if we haven't applied any commits
+    let mut had_successful_cherry_pick = false;
+    for commit in rev_list.lines() {
         info!("cherry-picking {commit}...");
-        git::cherry_pick(git::Commit(commit)).spawn()?;
 
-        maybe_prefix_cherry_picked_commit()
-    })?;
+        match git::cherry_pick(git::Commit(commit)).spawn() {
+            Err(e_cherry) => {
+                if !had_successful_cherry_pick {
+                    info!("failed on first commit");
+                    return Err(Error::Git(e_cherry))
+                } else if let Err(e_abort) = git::cherry_pick_abort().spawn() {
+                    info!("failed to abort cherry-pick");
+                    return Err(Error::Git(e_abort))
+                } else {
+                    info!("failed, stopping early");
+                    break
+                }
+            }
+            _ => had_successful_cherry_pick = true
+        }
+
+        maybe_prefix_cherry_picked_commit()?;
+    }
 
     info!("pushing branch...");
     git::push()