patch 8.1.0803: session file has problem with single quote in file name

Problem:    Session file has problem with single quote in file name. (Jon
            Crowe)
Solution:   Use a double quoted string.  Add a test.

src/ex_docmd.c

@@ -11838,9 +11838,9 @@ put_view(
 	     * edit that buffer, to not lose folding information (:edit resets
 	     * folds in other buffers)
 	     */
-	    if (fputs("if bufexists('", fd) < 0
+	    if (fputs("if bufexists(\"", fd) < 0
 		    || ses_fname(fd, wp->w_buffer, flagp, FALSE) == FAIL
-		    || fputs("') | buffer ", fd) < 0
+		    || fputs("\") | buffer ", fd) < 0
 		    || ses_fname(fd, wp->w_buffer, flagp, FALSE) == FAIL
 		    || fputs(" | else | edit ", fd) < 0
 		    || ses_fname(fd, wp->w_buffer, flagp, FALSE) == FAIL

src/testdir/test_mksession.vim

@@ -426,5 +426,19 @@ func Test_mksession_no_errmsg()
   call delete('Xtest_mks.out')
 endfunc
 
+func Test_mksession_quote_in_filename()
+  let v:errmsg = ''
+  %bwipe!
+  split another
+  split x'y\"z
+  mksession! Xtest_mks_quoted.out
+  %bwipe!
+  source Xtest_mks_quoted.out
+  call assert_true(bufexists("x'y\"z"))
+
+  %bwipe!
+  call delete('Xtest_mks_quoted.out')
+endfunc
+
 
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -791,6 +791,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    803,
 /**/
     802,
 /**/