MSVC build broken with perl 5.10

I just tried the MSVC build on a system with ActiveState Perl 5.10, and
it doesn't work. Some quick debugging before I downgraded to 5.8 showed
that this regexp in Project.pm line 262:
my $replace_re =
qr{^([^:\n\$]+\.c)\s*:\s*(?:%\s*: )?\$(\([^\)]+\))\/(.*)\/[^\/]+$};

matches things properly using Perl 5.8 in for example
src/bin/initdb/Makefile (matches a total of around 10 Makefiles), but
in 5.10 it simply does not match anything...

Any perl guru out there who can comment on why? ;-)

//Magnus