From time to time, I use https://metacpan.org/pod2html to check my POD. Recently, I noticed some strange behavior:

The following code renders as expected:

package FOO;
use strict;
use warnings;

sub foo {
  my $str = shift;
  return $str if $str =~ /^ssh\@github-/;
}
1;

__END__


=head1 NAME

Foo - The great Foo module
[download]

But if i change the "return" line like this, simply adding a \. to the regexp:

  return $str if $str =~ /^\.ssh\@github-/;
[download]

then i get "Error rendering POD - "

The error disappears when i use parens:

  return $str if ($str =~ /^\.ssh\@github-/);
[download]

Or, when i change the string "ssh" to something else, no error occurs:

  return $str if $str =~ /^\.sh\@github-/;
[download]

No error with the line above!

What's going on here? I would expect a POD renderer not to look at the active code at all. Is there perhaps a hidden feature that I'm conflicting with here?