patch 9.1.0752: can set 'cedit' to an invalid value

Problem:  can set cedit to an invalid value
Solution: Check that the value is a valid key name
          (Milly)

closes: #15778

Signed-off-by: Milly <milly.ca@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/ex_getln.c b/src/ex_getln.c
index ef7ca91..9d0695a 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -4445,7 +4445,7 @@
     else
     {
 	n = string_to_key(p_cedit, FALSE);
-	if (vim_isprintc(n))
+	if (n == 0 || vim_isprintc(n))
 	    return e_invalid_argument;
 	cedit_key = n;
     }
diff --git a/src/testdir/gen_opt_test.vim b/src/testdir/gen_opt_test.vim
index 7674714..c601158 100644
--- a/src/testdir/gen_opt_test.vim
+++ b/src/testdir/gen_opt_test.vim
@@ -72,7 +72,7 @@
       \ 'bufhidden': [['', 'hide', 'wipe'], ['xxx', 'hide,wipe']],
       \ 'buftype': [['', 'help', 'nofile'], ['xxx', 'help,nofile']],
       \ 'casemap': [['', 'internal'], ['xxx']],
-      \ 'cedit': [['', '\<Esc>'], ['xxx', 'f']],
+      \ 'cedit': [['', '^Y', '<Esc>'], ['xxx', 'f', '<xxx>']],
       \ 'clipboard': [['', 'unnamed', 'autoselect,unnamed', 'html', 'exclude:vimdisplay'], ['xxx', '\ze*', 'exclude:\\%(']],
       \ 'colorcolumn': [['', '8', '+2'], ['xxx']],
       \ 'comments': [['', 'b:#'], ['xxx']],
diff --git a/src/version.c b/src/version.c
index c6651c7..3743565 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    752,
+/**/
     751,
 /**/
     750,