http: len(x) fails if it doesn't fit into an int, use __len__() instead
len(x) raises OverflowError if it's bigger than 2**31-1, we need to call
__len__() ourself instead.
% hg debuginstall
Checking encoding (ascii)...
Checking extensions...
Checking templates...
Checking patch...
Checking commit editor...
Checking username...
No problems detected
% hg debuginstall with no username
Checking encoding (ascii)...
Checking extensions...
Checking templates...
Checking patch...
Checking commit editor...
Checking username...
no username supplied (see "hg help config")
(specify a username in your .hgrc file)
1 problems detected, please check your install!