patchable: Set the base branch as the git upstream branch (#1131)

* patchable: Set the base branch as the git upstream branch

This helps some git GUIs (like magit) narrow in on prioritizing our
patch commits, rather than just "the last N commits".

* Changelog

---------

Co-authored-by: Nick <10092581+NickLarsenNZ@users.noreply.github.com>

Author: nightkr

CHANGELOG.md

@@ -68,6 +68,7 @@ All notable changes to this project will be documented in this file.
 - BREAKING: kcat: Stop building kcat image ([#1124]).
 - containerdebug updated to 0.2.0 ([#1128])
 - Build Hadoop as `stackable` and configure the Stackable Nexus build-repo for the `root` user ([#1133])
+- patchable: The base branch is now configured as the git upstream branch ([#1131]).
 
 ### Fixed
 
@@ -151,6 +152,7 @@ All notable changes to this project will be documented in this file.
 [#1126]: https://github.com/stackabletech/docker-images/pull/1126
 [#1127]: https://github.com/stackabletech/docker-images/pull/1127
 [#1128]: https://github.com/stackabletech/docker-images/pull/1128
+[#1131]: https://github.com/stackabletech/docker-images/pull/1131
 [#1133]: https://github.com/stackabletech/docker-images/pull/1133
 
 ## [25.3.0] - 2025-03-21

rust/patchable/src/main.rs

@@ -426,6 +426,7 @@ fn main() -> Result<()> {
                 &ctx.pv.version,
                 &product_worktree_root,
                 &worktree_branch,
+                base_branch.as_deref(),
                 patched_commit,
             )
             .context(CheckoutProductWorktreeSnafu)?;

rust/patchable/src/repo.rs

@@ -1,9 +1,6 @@
 use std::path::{self, Path, PathBuf};
 
-use git2::{
-    FetchOptions, ObjectType, Oid, Repository, RepositoryInitOptions,
-    WorktreeAddOptions,
-};
+use git2::{FetchOptions, ObjectType, Oid, Repository, RepositoryInitOptions, WorktreeAddOptions};
 use snafu::{ResultExt, Snafu};
 
 use crate::{
@@ -215,6 +212,7 @@ pub fn ensure_worktree_is_at(
     worktree_name: &str,
     worktree_root: &Path,
     branch: &str,
+    base_branch: Option<&str>,
     commit: Oid,
 ) -> Result<()> {
     tracing::info!("checking out worktree");
@@ -242,29 +240,41 @@ pub fn ensure_worktree_is_at(
                         commit: head_commit,
                     })?;
             }
-            let branch = worktree
-                .branch(branch, &commit_obj, true)
-                .context(CreateWorktreeBranchSnafu {
+            let mut branch =
+                worktree
+                    .branch(branch, &commit_obj, true)
+                    .context(CreateWorktreeBranchSnafu {
+                        repo: &worktree,
+                        branch,
+                        commit,
+                    })?;
+            // Set the base branch as the patch branch's upstream, this helps some git GUIs (like magit)
+            // visualize the difference between upstream and our patchset.
+            if let Err(err) = branch.set_upstream(base_branch) {
+                tracing::warn!(
+                    error = &err as &dyn std::error::Error,
+                    branch.base = base_branch,
+                    "failed to set upstream branch, ignoring..."
+                );
+            }
+            let branch_ref = branch.into_reference();
+            let commit = branch_ref
+                .peel(ObjectType::Commit)
+                .context(FindCommitSnafu {
                     repo: &worktree,
-                    branch,
-                    commit,
-                })?
-                .into_reference();
-            let commit = branch.peel(ObjectType::Commit).context(FindCommitSnafu {
-                repo: &worktree,
-                commit: &branch,
-            })?;
+                    commit: &branch_ref,
+                })?;
             worktree
                 .checkout_tree(&commit, None)
                 .context(CheckoutWorktreeSnafu {
                     worktree: &worktree,
                     commit: &commit,
                 })?;
             worktree
-                .set_head_bytes(branch.name_bytes())
+                .set_head_bytes(branch_ref.name_bytes())
                 .context(UpdateWorktreeHeadSnafu {
                     worktree: &worktree,
-                    target: &branch,
+                    target: &branch_ref,
                 })?;
             Ok(())
         }