fix: util.root_pattern prioritises pattern order

doc/lspconfig.txt

@@ -371,7 +371,8 @@ below returns a function that takes as its argument the current buffer path.
 - `util.root_pattern`: function which takes multiple arguments, each 
   corresponding to a different root pattern against which the contents of the
   current directory are matched using |vim.fn.glob()| while traversing up the
-  filesystem.
+  filesystem. Parent directories are traversed once per pattern, in the order
+  the patterns are specified.
 >
    root_dir = util.root_pattern('pyproject.toml', 'requirements.txt')
 <

lua/lspconfig/util.lua

@@ -250,19 +250,22 @@ end
 
 function M.root_pattern(...)
   local patterns = vim.tbl_flatten { ... }
-  local function matcher(path)
+  return function(startpath)
+    startpath = M.strip_archive_subpath(startpath)
     for _, pattern in ipairs(patterns) do
-      for _, p in ipairs(vim.fn.glob(M.path.join(M.path.escape_wildcards(path), pattern), true, true)) do
-        if M.path.exists(p) then
-          return path
+      local match = M.search_ancestors(startpath, function(path)
+        for _, p in ipairs(vim.fn.glob(M.path.join(M.path.escape_wildcards(path), pattern), true, true)) do
+          if M.path.exists(p) then
+            return path
+          end
         end
+      end)
+
+      if match ~= nil then
+        return match
       end
     end
   end
-  return function(startpath)
-    startpath = M.strip_archive_subpath(startpath)
-    return M.search_ancestors(startpath, matcher)
-  end
 end
 
 function M.find_git_ancestor(startpath)

test/lspconfig_spec.lua

@@ -136,7 +136,7 @@ describe('lspconfig', function()
         -- change the working directory to test directory
         vim.api.nvim_command 'cd ./test/test_dir/a'
         local cwd = vim.fn.getcwd()
-        eq(true, cwd == lspconfig.util.root_pattern { 'root_marker.txt', 'a_marker.txt' }(cwd))
+        eq(true, cwd == lspconfig.util.root_pattern { 'a_marker.txt', 'root_marker.txt' }(cwd))
       end)
 
       it('resolves to root_marker.txt', function()