The problem with your code is the "BR|GR". Perl will now match any of these 2: 
\A [A-Z0-9]{8} BR

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OR: 
GR

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The second one matches. The solution would be to set $prompt_host to: 
$prompt_host = (?:BR|GR)

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In reply to Re^3: Regex matching after ASCII characters by elTriberium
in thread Regex matching after ASCII characters by Anonymous Monk

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