mcfly @0.7.1: upgrading shell integration results in prompts saying "error: The argument '--append-to-histfile <HISTFILE>' requires a value but none was supplied"

[cooljeanius (Eric Gallager)]

I recently upgraded mcfly to 0.7.1, and now after every shell prompt I get a message saying:

error: The argument '--append-to-histfile <HISTFILE>' requires a value but none was supplied

For more information try '--help'

The mcfly port already contains the following notes:

$ port notes mcfly
--->  mcfly has the following notes:
  If you are running bash as your shell, add:
      if [[ -r "/opt/local/share/mcfly/mcfly.bash" ]]; then
          source "/opt/local/share/mcfly/mcfly.bash"
      fi
  
  ...to your ~/.bashrc, then run:
      $ . ~/.bashrc
  
  If you are running zsh as your shell, add:
      if [[ -r "/opt/local/share/mcfly/mcfly.zsh" ]]; then
          source "/opt/local/share/mcfly/mcfly.zsh"
      fi
  
  ...to your .zshrc, then run:
      $ . ~/.zshrc
  
  If you are running fish as your shell, add:
      if [[ -r "/opt/local/share/mcfly/mcfly.fish" ]]; then
          source "/opt/local/share/mcfly/mcfly.fish"
      fi
  
  ...to your ~/.config/fish/config.fish, then run:
      $ source ~/.config/fish/config.fish

It seems as though these notes about shell integration might need to be updated? (I'm using bash for my shell, btw)