If that (update: oops... I meant to reply to that node) works for you, try this as a simplification (untested): 
$input_text =~ s{
    ^ ([#]{2,5}) \s+ [^\n]+ \s+ (?= ^ \1 [^#])
    }
    {}xmsg;

[download]
Beyond that, I have to say I don't understand your requirements. Can you express them more clearly?

Give a man a fish:  <%-{-{-{-<

In reply to Re: Tricky regex problem (updated) by AnomalousMonk
in thread Tricky regex problem by nysus

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