Package with changed PLIST can't be updated?

["Thomas Mueller" <mueller6724%twc.com@localhost>]

I'm trying to update my installed packages with pkg_rolling-replace, and get 
the error message about a conflicting PLIST with the new version.

When a package is upgraded, surely it is likely that there will be some 
different files, that's progress.  Maybe some files will be removed while other 
new files will appear in the new version.

This happened with ruby193-subversion and earlier with gcc48.

Error messages look like

=> Bootstrap dependency digest>=20010302: found digest-20121220
===> Building binary package for ruby200-subversion-1.8.9
=> Creating binary package /usr/packages/All/ruby200-subversion-1.8.9.tgz
/bin/ln -f 
/BETA1/pkgsrc/devel/ruby-subversion/work699.amd64/.packages/ruby200-subversion-1.8.9.tgz
 /usr/packages/All/ruby200-subversion-1.8.9.tgz 2>/dev/null ||  /bin/cp -pf 
/BETA1/pkgsrc/devel/ruby-subversion/work699.amd64/.packages/ruby200-subversion-1.8.9.tgz
 /usr/packages/All/ruby200-subversion-1.8.9.tgz
===> Install binary package of ruby200-subversion-1.8.9
pkg_add: Conflicting PLIST with ruby193-subversion-1.8.3nb1: 
lib/libsvn_swig_ruby-1.la
pkg_add: 1 package addition failed
*** Error code 1

Stop.
make[3]: stopped in /BETA1/pkgsrc/devel/ruby-subversion
*** Error code 1

Stop.
make[2]: stopped in /BETA1/pkgsrc/devel/ruby-subversion
*** Error code 1

Stop.
make[1]: stopped in /BETA1/pkgsrc/devel/ruby-subversion
*** Error code 1

Stop.
make: stopped in /BETA1/pkgsrc/devel/ruby-subversion

Same thing happened with lang/gcc48 (conflicting PLIST).

I wonder why I didn't run into this many more times previously.  Surely it 
can't be a new bug?

pkg_rolling-replace can't handle a change in the PLIST?

Do I need to pkg_delete the old package and pkg_add the new package?

I would of course, in pkg_add command, give the direct path to the newly-built 
package, maybe undefine (unset) PKG_PATH beforehand.

Tom