patch 8.0.0847: :argadd without argument can't handle space in file name

Problem:    :argadd without argument can't handle space in file name. (Harm te
            Hennepe)
Solution:   Escape the space. (Yasuhiro Matsumoto, closes #1917)
diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index 687bbae..381c5d1 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -2320,8 +2320,8 @@
  * Separate the arguments in "str" and return a list of pointers in the
  * growarray "gap".
  */
-    int
-get_arglist(garray_T *gap, char_u *str)
+    static int
+get_arglist(garray_T *gap, char_u *str, int escaped)
 {
     ga_init2(gap, (int)sizeof(char_u *), 20);
     while (*str != NUL)
@@ -2333,6 +2333,10 @@
 	}
 	((char_u **)gap->ga_data)[gap->ga_len++] = str;
 
+	/* If str is escaped, don't handle backslashes or spaces */
+	if (!escaped)
+	    return OK;
+
 	/* Isolate one argument, change it in-place, put a NUL after it. */
 	str = do_one_arg(str);
     }
@@ -2355,7 +2359,7 @@
     garray_T	ga;
     int		i;
 
-    if (get_arglist(&ga, str) == FAIL)
+    if (get_arglist(&ga, str, TRUE) == FAIL)
 	return FAIL;
     if (wig == TRUE)
 	i = expand_wildcards(ga.ga_len, (char_u **)ga.ga_data,
@@ -2401,6 +2405,7 @@
     char_u	*p;
     int		match;
 #endif
+    int		arg_escaped = TRUE;
 
     /*
      * Set default argument for ":argadd" command.
@@ -2410,12 +2415,13 @@
 	if (curbuf->b_ffname == NULL)
 	    return FAIL;
 	str = curbuf->b_fname;
+	arg_escaped = FALSE;
     }
 
     /*
      * Collect all file name arguments in "new_ga".
      */
-    if (get_arglist(&new_ga, str) == FAIL)
+    if (get_arglist(&new_ga, str, arg_escaped) == FAIL)
 	return FAIL;
 
 #ifdef FEAT_LISTCMDS
diff --git a/src/proto/ex_cmds2.pro b/src/proto/ex_cmds2.pro
index c873039..10277e8 100644
--- a/src/proto/ex_cmds2.pro
+++ b/src/proto/ex_cmds2.pro
@@ -52,7 +52,6 @@
 int check_changed_any(int hidden, int unload);
 int check_fname(void);
 int buf_write_all(buf_T *buf, int forceit);
-int get_arglist(garray_T *gap, char_u *str);
 int get_arglist_exp(char_u *str, int *fcountp, char_u ***fnamesp, int wig);
 void set_arglist(char_u *str);
 void check_arg_idx(win_T *win);
diff --git a/src/testdir/test_arglist.vim b/src/testdir/test_arglist.vim
index f75bad1..2a2425a 100644
--- a/src/testdir/test_arglist.vim
+++ b/src/testdir/test_arglist.vim
@@ -65,13 +65,19 @@
   %argd
   edit d
   arga
-  call assert_equal(len(argv()), 1)
-  call assert_equal(get(argv(), 0, ''), 'd')
+  call assert_equal(1, len(argv()))
+  call assert_equal('d', get(argv(), 0, ''))
+
+  %argd
+  edit some\ file
+  arga
+  call assert_equal(1, len(argv()))
+  call assert_equal('some file', get(argv(), 0, ''))
 
   %argd
   new
   arga
-  call assert_equal(len(argv()), 0)
+  call assert_equal(0, len(argv()))
 endfunc
 
 func Init_abc()
diff --git a/src/version.c b/src/version.c
index 9eb8b1a..0d144bb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    847,
+/**/
     846,
 /**/
     845,