filelog: add a hasnode() method (API)
Missing in the file storage interface is the ability to query whether
a specified value is a known node.
This commit defines that interface member and implements it on the
revlog and sqlite file stores.
Storage unit tests have been added.
The revlog implementation is a bit more complicated because index lookups
don't consistently raise the same exception. For SQLite, we can simply look
for a key in a dict.
Differential Revision: https://phab.mercurial-scm.org/D5163
{
"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"
}