sslutil: change comment and logged message for found ca cert file Future patches will change _defaultcacerts() to do something on platforms that aren't OS X. Change the comment and logged message to reflect the future.

tests: better testing of loaded certificates Tests were failing on systems like RHEL 7 where loading the system certificates results in CA certs being reported to Python. We add a feature that detects when we're able to load *and detect* the loading of system certificates. We update the tests to cover the 3 scenarios: 1) system CAs are loadable and detected 2) system CAs are loadable but not detected 3) system CAs aren't loadable

update: teach hg to override untracked dir with a tracked file on update This is a fix to an old problem when Mercurial got confused by an untracked folder with the same name as one of the files in a commit hg was trying to update to. It is pretty safe to remove this folder if it is empty. Backing up an empty folder seems to go against Mercurial's "don't track dirs" philosophy.

rebase: move handling of obsolete commits to be a separate RR class method