phases: update the phase set as we go during retract boundary Apparently iterating over the `changed_revs` dictionary is very expensive. On mozilla-try-2019-02-18, a perf::unbundle call with a 10 000 changesets bundle gives give use the following timing. e57d4b868a3e: 4.6 seconds ac1c75188440: 102.5 seconds prev-changeset: 30.0 seconds this-changeset: 4.6 seconds So, the performance regression is gone. Once again: thanks to marvelous Python!

{
    "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"
}