Do not show post detail published on a different site

[protoroto]

Description

Fix taken from pull request #725 from @adrien-delhorme . Added a test.

References

Fix #724

Fix #725

Checklist

• [x] I have read the contribution guide
• [x] Code lint checked via inv lint
• [x] changes file included (see docs)
• [ ] Usage documentation added in case of new features
• [x] Tests added

[coveralls]

coverage: 97.094%. remained the same when pulling 95cdf5a336d21e8e91d28b9968bc72b68848414b on protoroto:bugfix/issue-724-do-not-show-post-detail-on-different-site into 70a3d3749a68fef0db5881ec1f0a949e77fd5c03 on nephila:develop.

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (70a3d37) 94.24% compared to head (95cdf5a) 94.24%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #742 +/- ## ======================================== Coverage 94.24% 94.24% ======================================== Files 26 26 Lines 1824 1824 Branches 260 260 ======================================== Hits 1719 1719 Misses 53 53 Partials 52 52 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `94.24% <100.00%> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nephila#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://app.codecov.io/gh/nephila/djangocms-blog/pull/742?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nephila) | Coverage Δ | | |---|---|---| | [djangocms\_blog/views.py](https://app.codecov.io/gh/nephila/djangocms-blog/pull/742?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nephila#diff-ZGphbmdvY21zX2Jsb2cvdmlld3MucHk=) | `93.47% <100.00%> (ø)` | |

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.