web:cacert diables system wide CA

I need access to local hg repo via https which uses certificate signed by local CA. I've added cacerts parameter into [web] section of ~/.hgrc. In result only certificates signed by local CA can be checked. If I try to connect to bitbucket for example, I get error:

abort: error: _ssl.c:503: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

I wan't to be able use both local CA and system wide CA settings. In Natty all worked just fine, but after upgrade to Oneiric, cacerts overrides system list of CA. I suppose it is a regression bug.