tests: executable_spec: enable pending test #10443

Should hopefully work now after efc6d9951b.

test/functional/eval/executable_spec.lua

@@ -26,12 +26,7 @@ describe('executable()', function()
       eq('arg1=lemon;arg2=sky;arg3=tree;',
          call('system', sibling_exe..' lemon sky tree'))
     end
-    local is_executable = call('executable', sibling_exe)
-    if iswin() and is_executable ~= expected then
-      pending('XXX: sometimes fails on AppVeyor')
-    else
-      eq(expected, is_executable)
-    end
+    eq(expected, call('executable', sibling_exe))
   end)
 
   describe('exec-bit', function()