Sidebar: Create New Worktree only offers the current and default branch as a base

Reproduction steps 1. open project with multiple local andremote branches 2. Click add new agent thread 3. "new thread in" select "main" 4. Click "Create new worktree " Now you see not all branches shown in the dropdown Current vs. Expected behavior all branches should be shown in the dropdown Zed version and system specs Zed: v1.19.2+stable.356.df181c6f58d02677b385fa947d6bfde6d3530078 (Zed) OS: Linux X11 linuxmint 22.3 Memory: 31.1 GiB Architecture: x86_64 GPU: Intel(R) UHD Graphics 630 (CML GT2) || Intel open-source Mesa driver || Mesa 25.0.7-0ubuntu0.24.04.2 Attach Zed log file <details><summary>Zed.log</summary> <!-- Paste your log inside the code block. --> </details> Relevant Zed settings <details><summary>settings.json</summary> <!-- Paste your settings inside the code block. --> </details> Relevant Keymap <details><summary>keymap.json</summary> <…