Improve upstream commit filtering

Modified the logic in stacks.rs to filter upstream commits more accurately by comparing tree changes between the last local commit and the upstream commit being looked at. 

Added import for tree_changes function from but_core::diff module. Adjusted upstream commit processing to skip upstream commits that do not introduce new changes relative to the last local commit, preventing redundant upstream commits from being shown after operations such as squash or rebase.

Author: estib-vega

crates/but-workspace/src/stacks.rs

@@ -6,6 +6,7 @@ use crate::{RefInfo, StacksFilter, branch, head_info, ref_info, state_handle, ui
 use anyhow::{Context, bail};
 use bstr::BString;
 use but_core::RefMetadata;
+use but_core::diff::tree_changes;
 use but_graph::VirtualBranchesTomlMetadata;
 use gitbutler_command_context::CommandContext;
 use gitbutler_commit::commit_ext::CommitExt;
@@ -698,18 +699,37 @@ fn upstream_only_commits(
             // If the id matches verbatim or if there is a known remote_id (in the case of LocalAndRemote) that matchies
             c.id == commit.id().to_gix() || matches!(&c.state, CommitState::LocalAndRemote(remote_id) if remote_id == &commit.id().to_gix())
         });
+
         // Ignore commits that strictly speaking are remote only, but they match a known local commit (rebase etc)
-        if !matches_known_commit {
-            let created_at = i128::from(commit.time().seconds()) * 1000;
-            let upstream_commit = ui::UpstreamCommit {
-                id: commit.id().to_gix(),
-                message: commit.message_bstr().into(),
-                created_at,
-                author: commit.author().into(),
-            };
-            upstream_only.push(upstream_commit);
+        if matches_known_commit {
+            continue;
+        }
+
+        let last_local_commit = local_and_remote.last();
+
+        // If there's a last local commit, compare the trees
+        if let Some(last_local_commit) = last_local_commit {
+            let lhs = last_local_commit.id;
+            let rhs = commit.id().to_gix();
+
+            // We don't care about upstream commits that bring no new changes.
+            // This helps us avoid showing 'upstream commits' after squashing commits or rebasing.
+            let (changes, _) = tree_changes(repo, Some(lhs), rhs)?;
+            if changes.is_empty() {
+                continue;
+            }
         }
+
+        let created_at = i128::from(commit.time().seconds()) * 1000;
+        let upstream_commit = ui::UpstreamCommit {
+            id: commit.id().to_gix(),
+            message: commit.message_bstr().into(),
+            created_at,
+            author: commit.author().into(),
+        };
+        upstream_only.push(upstream_commit);
     }
+
     upstream_only.reverse();
 
     Ok(upstream_only)