view CONTRIBUTING @ 40002:0e8836be9541

storageutil: implement file identifier resolution method (BC)

revlog.lookup() has a number of advanced features, including partial
node matching.

These advanced features aren't needed for file id lookup because file
identifiers are almost always from internal sources. (An exception to
this is hgweb, which appears to have some code paths that attempt
to resolve a user-supplied string to a node.)

This commit implements a new function for resolving file identifiers
to nodes. It behaves like revlog.lookup() but without the
advanced features.

Tests reveal behavior changes:

* Partial hex nodes are no longer resolved to nodes.
* "-1" now returns nullid instead of raising LookupError.
* "0" on an empty store now raises LookupError instead of returning
  nullid.

I'm not sure why "-1" wasn't recognized before. But it seems reasonable
to accept it as a value since integer -1 resolves to nullid.

These changes all seem reasonable to me. And with the exception of
partial hex node matching, we may want to consider changing
revlog.lookup() as well.

Differential Revision: https://phab.mercurial-scm.org/D4797

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