Description

Title pretty much says it all. Antigen seems to rely on the fact that a repository has a 'master' branch and with Github's new default repository setup that uses 'main' instead (or any repository that changed their 'master' branch to 'main') installing/updating those plugins fails.

Steps to reproduce

Minimal steps to reproduce this behavior. Example:

1 - Use any theme/plugin that doesn't have a 'master' branch ([the theme I use](https://github.com/reobin/typewritten) is the one that was giving me issues)
2 - Run `antigen update`
    $ antigen update
    Updating reobin/typewritten@master... Error! Activate logging and try again.

Expected behavior:

- Plugins without a 'master' branch should work

Software version

• antigen version
  Antigen develop (d1dd78b)
  Revision date: 2018-01-15 14:37:21 -0300
• zsh --version
  zsh 5.8 (x86_64-ubuntu-linux-gnu)
• uname -a
  Linux poste-0948 5.4.0-51-generic Use user-provided version of zsh #56-Ubuntu SMP Mon Oct 5 14:28:49 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Configuration

• gist of .antigenrc
  Not used
• gist of .zshrc
  Entire file is here, but line 69 is where my theme that causes the issue is set.

More information

As a workaround you can manually clone/update your plugins in $ANTIGEN_BUNDLES (Antigen still creates the directory structure, just doesn't perform the clone/pull).