fix(build): Skip base_sha and base_ref when equal to head_sha during auto-inference (EME-607) (#2924)

## Summary

This PR modifies `sentry-cli` to skip setting `base_sha` and `base_ref`
when they are auto-inferred and `base_sha` equals `head_sha`.

## Changes

- Added tracking to distinguish between user-provided CLI arguments and
auto-inferred values for `base_sha` and `base_ref`
- When both values are auto-inferred and `base_sha == head_sha`, we now
set both to `None` before sending to the API
- User-provided values via `--base-sha` and `--base-ref` are always
respected regardless of their values

## Rationale

When `base_sha` equals `head_sha`, there is no meaningful comparison
baseline since we'd be comparing a commit against itself. This typically
occurs in certain CI scenarios where the auto-inference logic cannot
determine a proper base commit. By skipping these values, we allow the
backend to handle the comparison more appropriately.

Closes EME-607

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude <[email protected]>

Author: runningcode

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 - The `sentry-cli debug-files bundle-jvm` no longer makes any HTTP requests to Sentry, meaning auth tokens are no longer needed, and the command can be run offline ([#2926](https://github.com/getsentry/sentry-cli/pull/2926)).
 
+### Fixes
+
+- Skip setting `base_sha` and `base_ref` when they equal `head_sha` during auto-inference, since comparing a commit to itself provides no meaningful baseline ([#2924](https://github.com/getsentry/sentry-cli/pull/2924)).
+
 ## 2.58.0
 
 ### New Features

src/commands/build/upload.rs

@@ -230,7 +230,12 @@ pub fn execute(matches: &ArgMatches) -> Result<()> {
             base_repo_name,
         )
     };
-    let base_sha = matches
+
+    // Track whether base_sha and base_ref were explicitly provided by the user
+    let base_sha_from_user = matches.get_one::<String>("base_sha").is_some();
+    let base_ref_from_user = matches.get_one::<String>("base_ref").is_some();
+
+    let mut base_sha = matches
         .get_one("base_sha")
         .map(String::as_str)
         .map(Cow::Borrowed)
@@ -241,6 +246,24 @@ pub fn execute(matches: &ArgMatches) -> Result<()> {
                 .flatten()
                 .map(Cow::Owned)
         });
+
+    let mut base_ref = base_ref;
+
+    // If base_sha equals head_sha and both were auto-inferred, skip setting base_sha and base_ref
+    // but keep head_sha (since comparing a commit to itself provides no meaningful baseline)
+    if !base_sha_from_user
+        && !base_ref_from_user
+        && base_sha.is_some()
+        && head_sha.is_some()
+        && base_sha.as_deref() == head_sha.as_deref()
+    {
+        debug!(
+            "Base SHA equals head SHA ({}), and both were auto-inferred. Skipping base_sha and base_ref, but keeping head_sha.",
+            base_sha.as_deref().expect("base_sha is Some at this point")
+        );
+        base_sha = None;
+        base_ref = None;
+    }
     let pr_number = matches
         .get_one("pr_number")
         .copied()