Merge 0.7.13.0 - 0.7.13.3 from unstable.

* apt/cache.py:
  - add actiongroup() method (backport from 0.7.92)
  - re-work the logic in commit() to fail if installArchives() returns
    a unexpected result
* apt/progress/__init__.py:
  - catch exceptions in pm.DoInstall()
* apt/package.py:
  - Export if a package is an essential one (Closes: #543428)
* python/depcache.cc:
  - Make ActionGroups context managers so apt.Cache.actiongroup() has
    the same behavior as in 0.7.92
* apt/cache.py:
  - Add raiseOnError option to Cache.update() (Closes: #545474)
* apt/package.py:
  - Use the source version instead of the binary version in fetch_source().
* apt/progress/__init__.py:
  - Correctly ignore ECHILD by checking before EINTR (Closes: #546007)
* apt/cache.py:
 - Convert argument to str in __getitem__() (Closes: #542965).

1 files changed, 10 insertions, 3 deletions

diff --git a/apt/package.py b/apt/package.py
index 3b5cfccf..a811dfbb 100644
--- a/apt/package.py
+++ b/apt/package.py
@@ -521,10 +521,12 @@ class Version(object):
         acq = apt_pkg.Acquire(progress or apt.progress.text.AcquireProgress())
 
         dsc = None
-        src.lookup(self.package.name)
+        record = self._records
+        src.lookup(record.source_pkg)
+
         try:
-            while self.version != src.version:
-                src.lookup(self.package.name)
+            while record.source_ver != src.version:
+                src.lookup(record.source_pkg)
         except AttributeError:
             raise ValueError("No source for %r" % self)
         files = list()
@@ -692,6 +694,11 @@ class Package(object):
         This returns the same value as ID, which is unique."""
         return self._pkg.id
 
+    @property
+    def essential(self):
+        """Return True if the package is an essential part of the system."""
+        return self._pkg.essential
+
     @DeprecatedProperty
     def installedVersion(self): #pylint: disable-msg=C0103
         """Return the installed version as string.