This lib function applies a patch to the VCS_INFO_formats function
in zsh versions from v5.0.3 until v5.8, which don't quote % chars
in some arguments received. Normally that just means that some
% characters in these strings (branch names, directories, etc.)
will be incorrectly parsed as formatting sequences.
With CVE-2021-45444, however, this means that one of these strings
from a malicious source (e.g. a malicious git repository) can
trigger command injection and run arbitrary code in the user's
machine when visiting such git repository.
Zsh 5.8.1 fixes this vulnerability [1], but older vcs_info setups
still need a workaround such as this one to patch the vulnerability.
[1] c3ea1e5d52
Marc Cornellà