git: Add base branch support to create_branch (#42151)

Closes [#41674](https://github.com/zed-industries/zed/issues/41674)

Description:
Creating a branch from a base requires switching to the base branch
first, then creating the new branch and checking out to it, which
requires multiple operations.

Add base_branch parameter to create_branch to allow a new branch from a
base branch in one operation which is synonymous to the command `git
switch -c <new-branch> <base-branch>`.

Below is the video after solving the issue: 

(`master` branch is the default branch here, and I create a branch
`new-branch-2` based off the `master` branch. I also show the error
which used to appear before the fix.)

[Screencast from 2025-11-07
05-14-32.webm](https://github.com/user-attachments/assets/d37d1b58-af5f-44e8-b867-2aa5d4ef3d90)

Release Notes:

- Fixed the branch-picking error by replacing multiple sequential switch
operations with just one switch operation.

Signed-off-by: ayu-ch <ayu.chandekar@gmail.com>

crates/git/src/repository.rs

@@ -431,7 +431,8 @@ pub trait GitRepository: Send + Sync {
     fn branches(&self) -> BoxFuture<'_, Result<Vec<Branch>>>;
 
     fn change_branch(&self, name: String) -> BoxFuture<'_, Result<()>>;
-    fn create_branch(&self, name: String) -> BoxFuture<'_, Result<()>>;
+    fn create_branch(&self, name: String, base_branch: Option<String>)
+    -> BoxFuture<'_, Result<()>>;
     fn rename_branch(&self, branch: String, new_name: String) -> BoxFuture<'_, Result<()>>;
 
     fn worktrees(&self) -> BoxFuture<'_, Result<Vec<Worktree>>>;
@@ -1358,14 +1359,28 @@ impl GitRepository for RealGitRepository {
             .boxed()
     }
 
-    fn create_branch(&self, name: String) -> BoxFuture<'_, Result<()>> {
-        let repo = self.repository.clone();
+    fn create_branch(
+        &self,
+        name: String,
+        base_branch: Option<String>,
+    ) -> BoxFuture<'_, Result<()>> {
+        let git_binary_path = self.any_git_binary_path.clone();
+        let working_directory = self.working_directory();
+        let executor = self.executor.clone();
+
         self.executor
             .spawn(async move {
-                let repo = repo.lock();
-                let current_commit = repo.head()?.peel_to_commit()?;
-                repo.branch(&name, &current_commit, false)?;
-                Ok(())
+                let mut args = vec!["switch", "-c", &name];
+                let base_branch_str;
+                if let Some(ref base) = base_branch {
+                    base_branch_str = base.clone();
+                    args.push(&base_branch_str);
+                }
+
+                GitBinary::new(git_binary_path, working_directory?, executor)
+                    .run(&args)
+                    .await?;
+                anyhow::Ok(())
             })
             .boxed()
     }