patch 8.2.1673: complete_info() selected index has an invalid value

Problem:    complete_info() selected index has an invalid value. (Ben Jackson)
Solution:   Set the index when there is only one match. (closes #6945)
            Add test for complete_info().
diff --git a/src/version.c b/src/version.c
index 950ca40..f30daf8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1673,
+/**/
     1672,
 /**/
     1671,