Since you seem to just want the first group of digits:

use constant REVISION => ('$Id: mcdt.pl 2081 2006-08-25 16:16:27Z tomt
+e $' =~ /(\d+)/g)[0];
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should do it. No need for eval or substitution here.

Update: grr, I don't use g-less m// in list context often enough to remember what it returns.

use constant REVISION => '$Id: mcdt.pl 2081 2006-08-25 16:16:27Z tomte
+ $' =~ /(\d+)/;
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