util: drop local aliases for md5, sha1, sha256, and sha512 This used to be needed to paper over hashlib not being in all Pythons we support, but that's not a problem anymore, so we can simplify things a little bit.

cleanup: replace uses of util.(md5|sha1|sha256|sha512) with hashlib.\1 All versions of Python we support or hope to support make the hash functions available in the same way under the same name, so we may as well drop the util forwards.

pathencode: use hashlib.sha1 directly instead of indirecting through util

revlog: use hashlib.sha1 directly instead of through util Also remove module-local _sha alias, which was barely used.

store: use hashlib.sha1 directly instead of through util Also remove module-local alias to _sha, since it's not used that much.

similar: delete extra newline at EOF Spotted by my emacs config that cleans up extra whitespace.

scmutil: delete extra newline at EOF Spotted by my emacs config that cleans up extra whitespace.

graphmod: avoid sorting when already sorted This is somewhat redundant now, but allows us to add a toposort that should not be re-sorted either.

sslutil: per-host config option to define certificates Recent work has introduced the [hostsecurity] config section for defining per-host security settings. This patch builds on top of this foundation and implements the ability to define a per-host path to a file containing certificates used for verifying the server certificate. It is logically a per-host web.cacerts setting. This patch also introduces a warning when both per-host certificates and fingerprints are defined. These are mutually exclusive for host verification and I think the user should be alerted when security settings are ambiguous because, well, security is important. Tests validating the new behavior have been added. I decided against putting "ca" in the option name because a non-CA certificate can be specified and used to validate the server certificate (commonly this will be the exact public certificate used by the server). It's worth noting that the underlying Python API used is load_verify_locations(cafile=X) and it calls into OpenSSL's SSL_CTX_load_verify_locations(). Even OpenSSL's documentation seems to omit that the file can contain a non-CA certificate if it matches the server's certificate exactly. I thought a CA certificate was a special kind of x509 certificate. Perhaps I'm wrong and any x509 certificate can be used as a CA certificate [as far as OpenSSL is concerned]. In any case, I thought it best to drop "ca" from the name because this reflects reality.

tests: add basic tests for SMTP over SSL SSL handling in mail.py wasn't covered by our test suite, therefore it was sometimes broken. This patch introduces pretty minimal tests that only cover the default path. We can extend it later. Tested with python 2.6.9 and 2.7.11 on Debian sid.