DfsRefDatabase#compareAndPut had a vague semantics for reference
matching. Because of this, an operation to make a symbolic
reference had been broken for some DFS implementations even if they
followed the contract of compareAndPut. The clarified semantics
requires the implementations to satisfy the followings:

* Matching references should be both symbolic references or both
  object ID references.
* If both are symbolic references, both should have the same target
  name.
* If both are object ID references, both should have the same object
  ID.

This semantics is defined based on
https://git.eclipse.org/r/#/c/77416/. Before this commit,
DfsRefDatabase couldn't see the target of symbolic references.

InMemoryRepository is changed to comply with the new semantics. This
semantics change can affect the existing DFS implementations that only
checks object IDs. This commit adds two tests that the previous
InMemoryRepository couldn't pass.

Change-Id: I6c6b5d3cc8241a81f4a37782381c88e8a59fdf15
Signed-off-by: Masaya Suzuki <masayasuzuki@google.com>

The Repository class provides only one method to look up a ref by
name, getRef.  If I request refs/heads/master and that ref does not
exist, getRef will look further in the search path:

 ref/refs/heads/master
 refs/heads/refs/heads/master
 refs/remotes/refs/heads/master

This behavior is counterintuitive, needlessly inexpensive, and usually
not what the caller expects.

Allow callers to specify whether to use the search path by providing
two separate methods:

- exactRef, which looks up a ref when its exact name is known
- findRef, which looks for a ref along the search path

For backward compatibility, keep getRef as a deprecated synonym for
findRef.

This change introduces findRef and exactRef but does not update
callers outside tests to use them yet.

Change-Id: I35375d942baeb3ded15520388f8ebb9c0cc86f8c
Signed-off-by: Jonathan Nieder <jrn@google.com>

LocalDiskRepositoryTestCase and TestRepository have competing ideas
about time. Push them into MockSystemReader so they can
cooperate.

Rename getClock() methods that return Dates to getDate().

Change-Id: Ibbd9fe7f85d0064b0a19e3b675b9718a9e67c479
Signed-off-by: Terry Parker <tparker@google.com>

CherryPickCommand only works on a non-bare repository, as it must
modify the working tree and index in case of a merge conflict. In
tests, being able to recover from a merge conflict is less important,
as the caller should be able to control the full contents of files in
advance of the cherry-pick.

Change-Id: Ic332e44df1308b9336e884666b08c1f6db64513d

This includes both leaving existing Change-Ids alone (as, for example
Gerrit's commit-msg hook does) and programmatically setting a value.

Change-Id: Iaaffb0107ae27de24df1f0e95a8d628fb8ea5364

Change-Id: I343c3065fa369ef8aab2b033ac1e392b28d10daf

Change-Id: I6bcee635adda7c929f6fa68ef20438fe77e49184

Change-Id: I47082416f6e281262b160ba15272258f9109abd1

This flushed out a number of bugs in the way DfsRefUpdate, or at least
the InMemoryRepository implementation, processes symrefs. These have
been fixed, to an extent, in InMemoryRepository, but other
implementations may still suffer from these bugs.

Change-Id: Ifd12115a0060b9ff45a88d305b72f91ca0472f9a

Copied the implementation from CommitCommand.

Change-Id: Iade0e2d70bde70cfa830fe23bcc41959b011a14a