vim-patch:8.1.0651: :args \"foo works like :args without argument

Problem:    :args \"foo works like :args without argument.
Solution:   Fix check for empty argument. (closes vim/vim#3728)
2ac372ccee

src/nvim/ex_cmds2.c

@@ -1772,7 +1772,7 @@ void ex_args(exarg_T *eap)
     }
   }
 
-  if (!ends_excmd(*eap->arg)) {
+  if (*eap->arg != NUL) {
     // ":args file ..": define new argument list, handle like ":next"
     // Also for ":argslocal file .." and ":argsglobal file ..".
     ex_next(eap);

src/nvim/testdir/test_arglist.vim

@@ -170,6 +170,12 @@ func Test_argument()
   call assert_fails('argument', 'E163:')
 endfunc
 
+func Test_args_with_quote()
+  args \"foobar
+  call assert_equal('"foobar', argv(0))
+  %argdelete
+endfunc
+
 " Test for 0argadd and 0argedit
 " Ported from the test_argument_0count.in test script
 func Test_zero_argadd()