Test script for https://stackoverflow.com/q/50823740/827263

check-env

#!/usr/bin/perl

use strict;
use warnings;

my %saved_env = %ENV;
my $term = $ENV{TERM};

my $error_count = 0;
foreach my $var (sort keys %saved_env) {
    %ENV = ( TERM => $term, $var => $saved_env{$var});
    my $lines = 0;
    open my $PIPE, '-|', '/usr/bin/git', 'branch';
    while (<$PIPE>) {
        $lines ++;
    }
    close $PIPE;              
    if ($lines == 0) {
        print "$var=$ENV{$var} causes git branch to produce no output\n";
        $error_count ++;
    }
}

if ($error_count == 0) {
    print "No problem found\n";
}