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 #3728)
diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index c3f26b6..74d5642 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -2738,7 +2738,7 @@
 	    alist_new();
     }
 
-    if (!ends_excmd(*eap->arg))
+    if (*eap->arg != NUL)
     {
 	/*
 	 * ":args file ..": define new argument list, handle like ":next"
diff --git a/src/testdir/test_arglist.vim b/src/testdir/test_arglist.vim
index cb1117e..72e727f 100644
--- a/src/testdir/test_arglist.vim
+++ b/src/testdir/test_arglist.vim
@@ -217,6 +217,12 @@
   %argdelete
 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()
diff --git a/src/version.c b/src/version.c
index cbb0e70..3082c0d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -800,6 +800,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    651,
+/**/
     650,
 /**/
     649,