No need for a negative look-behind. 

while(<DATA>){
    chomp;
    print;
    print /^[^?]*<<\w+>>/ ? " - Match\n" : " - No Match\n";
}

__DATA__
http://www.google.com/?stuff=<<merge>>
http://<<merge>>.place.com/?blah=blahblah

[download]

prints

http://www.google.com/?stuff=<<merge>> - No Match
http://<<merge>>.place.com/?blah=blahblah - Match

In reply to Re: negative lookbehind question by thundergnat
in thread negative lookbehind question by shadowpuppet

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