copies: split the combination of the copies mapping in its own function
In some case, this part take up to 95% of the copy tracing that take about a
hundred second. This poor performance comes from the fact we keep duplciating
and merging dictionary that are mostly similar.
I want to experiment with smarter native code to do this, so I need to isolate
the function first.
{
"version": 1,
"project": "mercurial",
"project_url": "https://mercurial-scm.org/",
"repo": "..",
"branches": ["default", "stable"],
"environment_type": "virtualenv",
"show_commit_url": "https://www.mercurial-scm.org/repo/hg/rev/",
"benchmark_dir": "benchmarks",
"env_dir": "../.asv/env",
"results_dir": "../.asv/results",
"html_dir": "../.asv/html"
}