update the core-cpan-diff section a bit

diff --git a/Porting/release_managers_guide.pod b/Porting/release_managers_guide.pod
index 9dac56e..4034a68 100644 (file)
--- a/Porting/release_managers_guide.pod
+++ b/Porting/release_managers_guide.pod
@@ -190,23 +190,27 @@ but all I<must> be done in the run up to a release.
 
 =head3 dual-life CPAN module synchronisation
 
-Ensure that dual-life CPAN modules are synchronised with CPAN.  Basically,
-run the following:
+To see which core distro versions differ from the current CPAN versions:
 
-    $ ./perl -Ilib Porting/core-cpan-diff -a -o /tmp/corediffs
+    $ ./perl -Ilib Porting/core-cpan-diff -x -a
 
-to see any inconsistencies between the core and CPAN versions of distros,
-then fix the core, or cajole CPAN authors as appropriate. See also the
-C<-d> and C<-v> options for more detail.  You'll probably want to use the
-C<-c cachedir> option to avoid repeated CPAN downloads and may want to
-use C<-m file:///mirror/path> if you made a local CPAN mirror. Note that
-a minicpan mirror won't actually work, but can provide a good first pass
-to quickly get a list of modules which definitely haven't changed, to
-avoid having to download absolutely everything.
+Passing C<-u cpan> (and maybe C<-u undef>) will probably be helpful, since
+those are the only types of distributions that you can actually affect as a
+perl release manager (as opposed to a CPAN module maintainer).
 
-To see which core distro versions differ from the current CPAN versions:
+You can also run an actual diff of the contents of the modules, comparing core
+to CPAN, to ensure that there were no erroneous/extraneous changes that need to
+be dealt with. You do this by not passing the C<-x> option:
 
-    $ ./perl -Ilib Porting/core-cpan-diff -x -a
+    $ ./perl -Ilib Porting/core-cpan-diff -a -o /tmp/corediffs
+
+then fix the core, or cajole CPAN authors as appropriate. See also the C<-d>
+and C<-v> options for more detail (and the C<-u> option as mentioned above).
+You'll probably want to use the C<-c cachedir> option to avoid repeated CPAN
+downloads and may want to use C<-m file:///mirror/path> if you made a local
+CPAN mirror. Note that a minicpan mirror won't actually work, but can provide a
+good first pass to quickly get a list of modules which definitely haven't
+changed, to avoid having to download absolutely everything.
 
 If you are making a MAINT release, run C<core-cpan-diff> on both blead and
 maint, then diff the two outputs. Compare this with what you expect, and if