refactor: deprecate util.find_mercurial_ancestor

Work on #2079.

.github/ci/run_sanitizer.sh

@@ -15,7 +15,7 @@ if git diff --pickaxe-all -U0 -G "${SEARCH_PATTERN}" "${REF_BRANCH}" "${PR_BRANC
   exit 1
 fi
 
-SEARCH_PATTERN='(util\.path\.dirname|util\.path\.sanitize|util\.path\.exists|util\.path\.is_file|util\.path\.is_dir)'
+SEARCH_PATTERN='(util\.path\.dirname|util\.path\.sanitize|util\.path\.exists|util\.path\.is_file|util\.path\.is_dir|util\.find_mercurial_ancestor)'
 
 if git diff --pickaxe-all -U0 -G "${SEARCH_PATTERN}" "${REF_BRANCH}" "${PR_BRANCH}" -- '*.lua' | grep -Ev '\.lua$' | grep -E "^\+.*${SEARCH_PATTERN}" ; then
   echo

lua/lspconfig/util.lua

@@ -247,15 +247,6 @@ function M.find_git_ancestor(startpath)
   end)
 end
 
-function M.find_mercurial_ancestor(startpath)
-  return M.search_ancestors(startpath, function(path)
-    -- Support Mercurial directories
-    if vim.fn.isdirectory(M.path.join(path, '.hg')) == 1 then
-      return path
-    end
-  end)
-end
-
 function M.find_node_modules_ancestor(startpath)
   return M.search_ancestors(startpath, function(path)
     if vim.fn.isdirectory(M.path.join(path, 'node_modules')) == 1 then
@@ -405,4 +396,9 @@ function M.path.exists(filename)
   return stat and stat.type or false
 end
 
+--- @deprecated use `vim.fs.find('.hg', { path = startpath, upward = true })` instead
+function M.find_mercurial_ancestor(startpath)
+  return vim.fs.find('.hg', { path = startpath, upward = true })
+end
+
 return M