strange map $request issue (4 replies)

For example:

map $request $testvar {
default 0;
~*montytest 1;
}

if ($testvar) { return 412; }

[20/Jun/2014:xx:xx:20 +0200] 69.64.xxxx:52393 - - "GET /montytest/ HTTP/1.1" 412 712 "-" "Mozilla/5.0........

[20/Jun/2014:xx:xx:29 +0200] 115.254.xxxx:59855 - - "HEAD /montytest/ HTTP/1.1" 400 0 "-" "-" "-" -

Why does a GET work but not a HEAD ??