Where you have s{$tag=(.*?)\&}, just make it s{$tag=(.*?)(?:\&|$)}. So you match an ampersand or the end of string. Another way: s{$tag=([^&]*?)} should work
Caution: Contents may have been coded under pressure.

In reply to Re: edge case in substitution? by Roy Johnson
in thread edge case in substitution? by Anonymous Monk

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