Como posso instalar python-dev off apt-get?

Eu tentei isso e isso e isso e isso

Nenhum deles instala o python-dev, eu tenho meu sistema amd64, 14.04 instalado e funcionando, enquanto tento instalar o wagtail, um django cms, recebo o erro:

     pysass.c:4:20: fatal error: Python.h: No such file or directory

     #include <Python.h>

                        ^

    compilation terminated.

    error: command 'x86_64-linux-gnu-gcc' failed with exit status 1

    ----------------------------------------
    Cleaning up...
    Command /usr/bin/python -c "import setuptools, tokenize;__file__='/tmp/pip_build_root/
    libsass/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace
    ('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-ojWg1O-record/install-
    record.txt --single-version-externally-managed --compile failed with error code 1 in 
    /tmp/pip_build_root/libsass
    Storing debug log for failure in /home/payload/.pip/pip.log

Como posso corrigir isso e instalar o pacote?

É por causa do Python.hcabeçalho c ausente que está incluído no python-devpacote.

Quando tentei os links acima, ele diz:

apt-get install python-dev

Package python-dev is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  python

E: Package 'python-dev' has no installation candidate

para apt-get install python2.7-dev

Package python2.7-dev is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'python2.7-dev' has no installation candidate

Eu pesquisei nos arquivos debian e encontrei um pacote, python 2.7.8-1mas que não pôde ser instalado.

Tentei isso na barra de lançamento também, mas não funciona.

Tem certeza de que está fazendo certo?

Esta é a minha saída para # apt-get install python2.7-dev

root@olympus:/home/zeus# apt-get install python2.7-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  libexpat1-dev libpython2.7-dev
The following NEW packages will be installed:
  libexpat1-dev libpython2.7-dev python2.7-dev
0 upgraded, 3 newly installed, 0 to remove and 7 not upgraded.
Need to get 22.4 MB of archives.
After this operation, 35.0 MB of additional disk space will be used.
Do you want to continue? [Y/n]

Tente fazer isso como root ( su)

Além disso, tente executar # apt updatee verifique se o Multiverse e o universo estão ativados (consulte Como ativar o repositório "Universe"? ). Também habilitei backports no meu sistema, não tenho certeza se isso faz alguma diferença nesse caso.