fix(vcs): Handle non-github workflow in find_base_sha

`find_head_sha` supported both Github workflow contexts and 'raw git'
contexts however the matching function `find_base_sha` did not handle
raw git contexts.

Thi updates `find_base_sha` to return the equivalent of:
`git merge-base HEAD origin/HEAD`. For:

```
     o---o---o---origin/main
    /
---1---o---o---o---foo
```

We return the SHA of 1.

Author: chromy

CHANGELOG.md

@@ -11,6 +11,10 @@
 
 - Fix autofilled git base metadata (`--base-ref`, `--base-sha`) when using the `build upload` subcommand in git repos. Previously this worked only in the contexts of GitHub workflows ([#2897](https://github.com/getsentry/sentry-cli/pull/2897)).
 
+### Fixes
+
+- Fix auto filled git metadata when using the `build upload` subcommand in non-github workflow contexts ([#2897](https://github.com/getsentry/sentry-cli/pull/2897))
+
 ## 2.57.0
 
 ### New Features

src/utils/vcs.rs

@@ -3,7 +3,7 @@
 use std::fmt;
 use std::path::PathBuf;
 
-use anyhow::{bail, format_err, Context as _, Error, Result};
+use anyhow::{bail, format_err, Error, Result};
 use chrono::{DateTime, FixedOffset, TimeZone as _};
 use git2::{Commit, Repository, Time};
 use if_chain::if_chain;
@@ -579,13 +579,18 @@ pub fn find_base_sha(remote_name: &str) -> Result<Option<String>> {
         return Ok(Some(pr_base_sha));
     }
 
+<<<<<<< HEAD
     let repo = git2::Repository::open_from_env().context("Could not open repository")?;
+=======
+    let repo = git2::Repository::open_from_env()?;
+>>>>>>> 4f1cba4a (fix(vcs): Handle non-github workflow in find_base_sha)
 
     let head_commit = repo.head()?.peel_to_commit()?;
 
     let remote_branch_name = format!("refs/remotes/{remote_name}/HEAD");
     let remote_ref = repo
         .find_reference(&remote_branch_name)
+<<<<<<< HEAD
         .with_context(|| "Could not find default branch for {remote_name}")?;
 
     Ok(remote_ref
@@ -594,6 +599,15 @@ pub fn find_base_sha(remote_name: &str) -> Result<Option<String>> {
         .map(|oid| oid.to_string())
         .ok()
         .inspect(|sha| debug!("Found merge-base commit as base reference: {sha}")))
+=======
+        .map_err(|e| anyhow::anyhow!("Could default branch for {remote_name}: {e}"))?;
+
+    let remote_commit = remote_ref.peel_to_commit()?;
+    let merge_base_oid = repo.merge_base(head_commit.id(), remote_commit.id())?;
+    let merge_base_sha = merge_base_oid.to_string();
+    debug!("Found merge-base commit as base reference: {merge_base_sha}");
+    Ok(Some(merge_base_sha))
+>>>>>>> 4f1cba4a (fix(vcs): Handle non-github workflow in find_base_sha)
 }
 
 /// Extracts the PR head SHA from GitHub Actions event payload JSON.