Add Breaks: for older versions of breezy/bzr-git since they use Dulwich' private packs API, which has changed.

debian/changelog

@@ -1,6 +1,8 @@
 dulwich (0.19.11-2) UNRELEASED; urgency=medium
 
   * Re-export upstream signing key without extra signatures.
+  * Add Breaks: for older versions of breezy/bzr-git since they use
+    Dulwich' private packs API, which has changed.
 
  -- Jelmer Vernooij <jelmer@debian.org>  Sat, 09 Feb 2019 07:36:34 +0000
 

debian/control

@@ -30,7 +30,7 @@ Depends: python-certifi,
          ${misc:Depends},
          ${python:Depends},
          ${shlibs:Depends}
-Breaks: bzr-git (<< 0.6.2)
+Breaks: bzr-git (<< 0.6.13+bzr1650), python-breezy (<< 3.0.0~bzr7268)
 Recommends: python-fastimport
 Suggests: python-gpg
 Description: Python Git library
@@ -69,7 +69,7 @@ Depends: python3-certifi,
          ${misc:Depends},
          ${python3:Depends},
          ${shlibs:Depends}
-Breaks: bzr-git (<< 0.6.2)
+Breaks: python3-breezy (<< 3.0.0~bzr7268)
 Recommends: python3-fastimport
 Suggests: python3-gpg
 Description: Python Git library - Python3 module