zsh allows Filename Generation and Pattern Matching (Globbing) using square brackets and other characters (explained in the zsh guide, section 5.9).
That may cause problem with shell commands that use square brackets, such as some rake tasks. The error message is a cryptic
zsh: no matches found.
The solution, found in the zsh FAQ (section 3.4), is simply adding a line in ~/.zshrc that disables globbing for a single command:
alias rake="noglob rake"