The idea is simple. If the given node id prefix is 'ff...f', add +1 to the
number of matches (e.g. ambiguous if partial + maybewdir > 1).
This patch also fixes id() revset and shortest() template since _partialmatch()
can raise WdirUnsupported exception.
Previously the added/modified placeholder hash for manifests generated from the
dirstate was a 21byte long string consisting of the p1 file hash plus a single
character to indicate an add or a modify. Normal hashes are only 20 bytes long.
This makes it complicated to implement more efficient manifest implementations
which rely on the hashes being fixed length.
Let's change this hash to just be 20 bytes long, and rely on the astronomical
improbability of an actual hash being these 20 bytes (just like we rely on no
hash every being the nullid).
This changes the possible behavior slightly in that the hash for all
added/modified entries in the dirstate manifest will now be the same (so simple
node comparisons would say they are equal), but we should never be doing simple
node comparisons on these nodes even with the old hashes, because they did not
accurately represent the content (i.e. two files based off the same p1 file
node, with different working copy contents would have the same hash (even with
the appended character) in the old scheme too, so we couldn't depend on the
hashes period).
Previously the new-node placeholder hash for manifests generated from the
dirstate was a 21byte long string of "!" characters. Normal hashes are only 20
bytes long. This makes it complicated to implement more efficient manifest
implementations which rely on the hashes being fixed length.
Let's change this hash to just be 20 bytes long, and rely on the astronomical
improbability of an actual hash being 20 "!" bytes in a row (just like we rely
on no hash ever being the nullid).
A future diff will do this for added and modified dirstate markers as well, so
we're putting the new newnodeid in node.py so there's a common place for these
placeholders.
Python 3's hex() insists on operating on bytes. This patch gives
it what it wants.
'' and b'' in Python 2 are equivalent, so this has no impact on
Python 2.
The "ff..." node was introduced at 187c3ec3d83f, and we also need an integer
that can be processed in revset. We could use len(repo), but it would be
likely to hide possible bugs. Instead, using INT_MAX, we can notice such bugs
by IndexError, at the cost of handling non-contiguous revisions.