copies: create helper for getting all copies for changeset There are a few places where we get all the copies for a changeset (at least the {file_copies} template and in two places in `hg log --copies` code). These places currently call scmutil.getrenamedfn() to get a caching "getrenamed" function. They all use it in a similar way. We will be able to reuse more code by having a function for getting all the copies for a changeset. This patch introduces such a function. It uses it in the {file_copies} template to show that it works. It relies on the existing scmutil.getrenamedfn() for caching in the filelog-centric case. Differential Revision: https://phab.mercurial-scm.org/D6545

logcmdutil: also check for copies in null revision and working copy It's safe (and fast) to look for copies in the null revision, and it's incorrect not to look for them in the working copy, so let's look in both places. Differential Revision: https://phab.mercurial-scm.org/D6544