"Unable to fork!" error on launch and subsequent new window/tabs on macOS beta 3

Thanks for filing an issue! Please answer the questions below so I can help you.

• iTerm2 version: Build 3.0.4
• OS version: 10.12 Beta (16A254g)
• Attach com.googlecode.iterm2.plist here (drag-drop from finder into this window)
• Attach a debug log, if possible. Instructions at debuglog.txt
• Are you reporting a performance issue or a hang? Please attach a sample. Instructions at https://gitlab.com/gnachman/iterm2/wikis/HowToSample

Detailed steps to reproduce the problem:

1. Launch app on macOS version specified above.
2. That’s it.
3. Launch new tab / window to reproduce every time.

What happened:

Error dialog (see screenshot): "Unable to fork!" "iTerm cannot launch the program for this session."

What should have happened:

A session should have launched.

My shell is zsh, in case that matters.