The comparison of a job's repository URL and the URL passed to notifyCommit will fail when the 2 URLs differ slightly, even though they point to the same place.

Example that triggers the problem:

Repository URL (in job configuration screen): http://mymercurialrepo.com.br/hg/main/myproj/
hook configuration:
[hooks]
commit.jenkins = wget -q -O /dev/null http://myjenkins.com.br/jenkins/mercurial/notifyCommit?url=http://mymercurialrepo.com.br/hg/main/myproj
incoming.jenkins = wget -q -O /dev/null http://myjenkins.com.br/jenkins/mercurial/notifyCommit?url=http://mymercurialrepo.com.br/hg/main/myproj

The URL comparison should first transform both URLs to their canonical form (by appending a slash at the end if one is missing, for instance).

I guess it will also fail if one of the URLs includes an HTTP redirect.