bump perl5db.pl's $VERSION

Add a note about version numbering, since if we use X.XX_XX versions
in blead it's harder to find an unused version number if the module
is modified in maint.

Author: tonycoz

lib/perl5db.pl

@@ -528,7 +528,8 @@ BEGIN
 # Debugger for Perl 5.00x; perl5db.pl patch level:
 use vars qw($VERSION $header);
 
-$VERSION = '1.49_04';
+# bump to X.XX in blead, only use X.XX_XX in maint
+$VERSION = '1.50';
 
 $header = "perl5db.pl version $VERSION";