incorrect dependencies in debian/control file

marc@ubuntu:~$ grep ^deb /etc/apt/sources.list
deb http://archive.canonical.com/ubuntu feisty-commercial main
deb http://ch.archive.ubuntu.com/ubuntu/ feisty main restricted universe multiverse
deb http://ch.archive.ubuntu.com/ubuntu/ feisty-updates main restricted universe multiverse
deb http://ch.archive.ubuntu.com/ubuntu/ feisty-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu/ feisty-security main restricted universe multiverse

marc@ubuntu:~$ sudo apt-get install idle
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.

Since you only requested a single operation it is extremely likely that
the package is simply not installable and a bug report against
that package should be filed.
The following information may help to resolve the situation:

The following packages have unmet dependencies.
  idle: Depends: python (= 2.5.1~rc1-0ubuntu3) but 2.5.1-0ubuntu1 is to be installed
E: Broken packages

1) this problem also occurs when trying to install python-all, python-dev and other packages from the same source-package

2) as for "idle", shouldn't a dependency on idle-python2.5 be added ? Even if the dependencies weren't broken "apt-get install idle" wouldn't install idle.

Thanks !