patch 8.2.4566: check for existing buffer in session file may not work

Problem:    Check for existing buffer in session file does not work for files
            in the home directory.
Solution:   Use fnamemodify(). (James Cherti, closes #9945)  Add a test.
diff --git a/src/version.c b/src/version.c
index 2ea5965..5576f20 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4566,
+/**/
     4565,
 /**/
     4564,