Tor Browser macOS dmg's are not mountable on some systems
We have reports that our .dmg images are not mountable on some macOS systems (one report for 10.12.5 (https://lists.torproject.org/pipermail/tbb-dev/2017-July/000589.html) and one for 10.9 (https://blog.torproject.org/comment/271292#comment-271292)).
The error message is something like:
image could no be mounted no mountable file system
This happens while other .dmgs work fine on those systems.