fix perl5db.pl to import the correct feature bundle

Author: book

lib/perl5db.pl

@@ -523,7 +523,7 @@ package DB;
 
 BEGIN {
     require feature;
-    $^V =~ /^v(\d+\.\d+)/;
+    $^V =~ /^v(5\.\d+|\d+)/;
     feature->import(":$1");
     $_initial_cwd = Cwd::getcwd();
 }