Fix merge errors in git_handler.py (#305)

mentat/git_handler.py

@@ -7,14 +7,6 @@
 from mentat.session_context import SESSION_CONTEXT
 
 
-def get_git_diff_for_path(path: Path) -> str:
-    session_context = SESSION_CONTEXT.get()
-    git_root = session_context.git_root
-    return subprocess.check_output(
-        ["git", "diff", path], cwd=git_root, text=True, stderr=subprocess.DEVNULL
-    )
-
-
 def get_non_gitignored_files(path: Path) -> set[Path]:
     return set(
         # git returns / separated paths even on windows, convert so we can remove
@@ -181,9 +173,6 @@ def check_head_exists() -> bool:
     git_root = session_context.git_root
 
     try:
-        subprocess.check_output(
-            ["git", "rev-parse", "HEAD", "--"], cwd=git_root, stderr=subprocess.DEVNULL
-        )
         subprocess.check_output(
             ["git", "rev-parse", "HEAD", "--"], cwd=git_root, stderr=subprocess.DEVNULL
         )