Don't query cache[].candidate.version when no cache[].candidate is available

1 files changed, 3 insertions, 1 deletions

diff --git a/apt/debfile.py b/apt/debfile.py
index 469cbb36..f74b6981 100644
--- a/apt/debfile.py
+++ b/apt/debfile.py
@@ -347,8 +347,10 @@ class DebPackage(object):
         if pkgname in self._cache:
             if use_installed and self._cache[pkgname].installed:
                 cachever = self._cache[pkgname].installed.version
-            else:
+            elif self._cache[pkgname].candidate:
                 cachever = self._cache[pkgname].candidate.version
+            else:
+                return self.VERSION_NONE
             if cachever is not None:
                 cmp = apt_pkg.version_compare(cachever, debver)
                 self._dbg(1, "CompareVersion(debver,instver): %s" % cmp)