patch 8.0.1426: "gf" and <cfile> don't accept ? and & in URL commit https://github.com/vim/vim/commit/9e3dfc650190e96739abc004eb9948afa68136b4 Author: Bram Moolenaar <Bram@vim.org> Date: Mon Dec 25 14:29:18 2017 +0100 patch 8.0.1426: "gf" and <cfile> don't accept ? and & in URL Problem: "gf" and <cfile> don't accept ? and & in URL. (Dmitrii Tcyganok) Solution: Check for a URL and allow for extra characters. (closes https://github.com/vim/vim/issues/2493)

function Test_Comparators()
  try
    let oldisident=&isident
    set isident+=#
    call assert_equal(1, 1 is#1)
  finally
    let &isident=oldisident
  endtry
endfunction