perf(git): run rev-parse and git show <commit> sync

lua/git/repo.lua

@@ -322,35 +322,26 @@ function M.head(path)
     return nil
 end
 
----Resolve a git revision to its object SHA. Calls `callback(sha?)` on the
----main loop with nil if the ref can't be parsed (root-commit's `^`, blob's
----`^`, malformed ref, etc.). When `short` is true, the result is abbreviated
----via `core.abbrev` (auto-extended by git to keep the prefix unique in the
----current repo).
+---Resolve a git revision to its object SHA. Returns nil if the ref can't
+---be parsed (root-commit's `^`, blob's `^`, malformed ref, etc.). When
+---`short` is true, the result is abbreviated via `core.abbrev`
+---(auto-extended by git to keep the prefix unique in the current repo).
 ---@param worktree string
 ---@param ref string
 ---@param short boolean
----@param callback fun(sha: string?)
-function M.rev_parse(worktree, ref, short, callback)
+---@return string?
+function M.rev_parse(worktree, ref, short)
     local cmd = { "git", "rev-parse", "--verify", "--quiet" }
     if short then
         table.insert(cmd, "--short")
     end
     table.insert(cmd, ref)
-    vim.system(
-        cmd,
-        { cwd = worktree, text = true },
-        vim.schedule_wrap(function(result)
-            local sha
-            if result.code == 0 then
-                local trimmed = vim.trim(result.stdout or "")
-                if trimmed ~= "" then
-                    sha = trimmed
-                end
-            end
-            callback(sha)
-        end)
-    )
+    local result = vim.system(cmd, { cwd = worktree, text = true }):wait()
+    if result.code ~= 0 then
+        return nil
+    end
+    local trimmed = vim.trim(result.stdout or "")
+    return trimmed ~= "" and trimmed or nil
 end
 
 return M