This has been an interesting thread so out of curiosity I happened to check on the bug report. According to Dave Mitchell:

Thanks for the report. This is fixed in perl 5.9.5 onwards, probably by change #31203. PL_in_my wasn't being re-initialised at the start of the eval, so '$string' was being misinterpreted as 'my $string'.

Looks like Somni had it right in Re: Bug : eval and accent.