invoke `pycentral pkgremove foo` in preinst if upgrading from python-central based package

autoscripts/preinst-pycentral-clean

+# make sure python-central files are removed before new package is installed
+if [ -f /var/lib/pycentral/#PACKAGE#.pkgremove ] || [ -f /var/lib/pycentral/pkgremove ]
+then
+	pycentral pkgremove #PACKAGE#
+	rm -f /var/lib/pycentral/#PACKAGE#.pkgremove
+fi

debian/changelog

+python-defaults (2.6.5-6) UNRELEASED; urgency=low
+
+  * dh_python2:
+    - invoke `pycentral pkgremove foo` in preinst if upgrading from
+      python-central based package
+
+ -- Piotr Ożarowski <piotr@debian.org>  Sun, 27 Jun 2010 13:20:01 +0200
+
 python-defaults (2.6.5-5) unstable; urgency=medium
 
   * Use Python's compileall module instead of pycompile to byte-compile

dh_python2

@@ -564,6 +564,7 @@ def main():
 
         pyclean_added = False  # invoke pyclean only once in maintainer script
         if stats['compile']:
+            dh.autoscript(package, 'preinst', 'preinst-pycentral-clean', '')
             dh.autoscript(package, 'postinst', 'postinst-pycompile', '')
             dh.autoscript(package, 'prerm', 'prerm-pyclean', '')
             pyclean_added = True