broken by the FPATH environment variable defined by bash / lmod

[Vincent Lefevre <vincent@xxxxxxxxxx>]

FYI, I've just reported the following bug:

  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1144635

Package: zsh
Version: 5.9-8+b23
Severity: serious
Tags: upstream

On a machine that has just been upgraded to trixie, I start zsh
via a bash login shell (run by sshd). The issue is that when it
is a login shell, bash defines the $FPATH environement variable
to '/usr/share/lmod/lmod/init/ksh_funcs' as shown by

  echo "FPATH = '$FPATH'" >&2

at the beginning of the ~/.bash_profile file, which outputs:

FPATH = '/usr/share/lmod/lmod/init/ksh_funcs'

This is possibly due to /usr/share/lmod/8.7.60/init/bash from the
lmod package, as mentioned at

  https://github.com/direnv/direnv/issues/858

(note that I'm not a direnv user... this was found by Google + AI).

Such a setting completely breaks zsh, which outputs

zsh:1: url-quote-magic: function definition file not found

each time I type a key (the key has no other effect, i.e. the
command line at the prompt remains empty, so I need to type Ctrl-D
to quit zsh).

It appears that instead of ignoring the $FPATH environment variable
on startup, zsh sets $fpath to $FPATH.

Note that the zshparam(1) man page says: "Some environment variables
are not imported for reasons of security or because they would
interfere with the correct operation of other shell features.",
which should be the case here.

-- 
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon)