Prevent hang in git cat-file if the repository is not a valid repository (Partial...

Prevent hang in git cat-file if the repository is not a valid repository (Partial #17991) (#17992)

* Prevent hang in git cat-file if the repository is not a valid repository (Partial #17991)

Unfortunately it appears that if git cat-file is run in an invalid
repository it will hang until stdin is closed. This will result in
deadlocked /pulls pages and dangling git cat-file calls if a broken
repository is tried to be reviewed or pulls exists for a broken
repository.

Signed-off-by: Andrew Thornton <art27@cantab.net>
* placate lint

Signed-off-by: Andrew Thornton <art27@cantab.net>
* fix compilation bug

Signed-off-by: Andrew Thornton <art27@cantab.net>
* Add the missing directories to the testrepos

* fixup! Add the missing directories to the testrepos

* and ensure that all of the other places have the objects directories too

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>