This reverts commit 6bc48cdc62.

Until git v1.7.10.2~29^2~1 (builtin/merge.c: reduce parents early,
2012-04-17), C git merge would make merge commits with duplicate parents
when asked to with a series of commands like the following:

  git checkout origin/master
  git merge --no-ff origin/master

Nowadays "git merge" removes redundant parents more aggressively
(whenever one parent is an ancestor of another and not just when
duplicates exist) but merges with duplicate parents are still permitted
and can be created with git fast-import or git commit-tree and history
viewers need to be able to cope with them.

CommitBuilder is an interface analagous to commit-tree, so it should
allow duplicate parents.  (That said, an option to automatically remove
redundant parents would be useful.)

Reported-by: Dave Borowitz <dborowitz@google.com>
Change-Id: Ia682238397eb1de8541802210fa875fdd50f62f0
Signed-off-by: Jonathan Nieder <jrn@google.com>

When setting the parents of a commit with setParentIds() or
addParentId() it should be checked that we don't have duplicate parents.
An IllegalArgumentException should be thrown in this case.

Change-Id: I9fa9f31149b7732071b304bca232f037146de454
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>

Bug: 443006
Change-Id: I40b1eb044fa2d9e6c5d4b956c17e32ca6c1bd39f
Signed-off-by: Konrad Kügler <swamblumat-eclipsebugs@yahoo.de>

The aim of this change is to place all commits of a branch on the same
lane and commits of other (side) branches on different lanes.

The algorithm treats first parents of a commit specially by placing them
on the same lane as the commit itself. When a commit is the first parent
of multiple children it could be placed on any of these children's
lanes. In this case it is placed on the longest child lane, as this is
usually the lane of the branch the commit actually was made on.

Other (non-first) parents are placed on new lanes. This creates a layout
that should make it easier to see branches and merges and follow linear
branch histories.
This differs from the previous approach, which sometimes plotted the
commits of a side branch on the same lane as the base branch commits and
further commits on the base branch appeared on a different lane.
This made the base branch appear as if it was the side branch and
the side branch appears to be the base branch.

In addition to lane assignment, also the plotting code changed to start
drawing a branch lane from the commit where it forks out. Previously it
started only when the first commit on the branch appeared.

Active lanes are continued with every commit that is processed.
Previously lanes were only continued when the next commit on the lane
was encountered. This could produce (temporarily) dangling commits if
the next commit on the lane was not processed yet.

CQ: 8299
Bug: 419359
Bug: 434945
Change-Id: Ibe547aa24b5948ae264f7d0f56a492a4ef335608
Signed-off-by: Konrad Kügler <swamblumat-eclipsebugs@yahoo.de>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

When more than one lane is drawn, some commits are vertically misaligned
(off by two pixels). This change fixes the alignment.

Bug: 426047
Change-Id: Icbe7ce9f5a6b281b2aaab66e4d76dfc1010b2fb5
Signed-off-by: Konrad Kügler <swamblumat-eclipsebugs@yahoo.de>
Signed-off-by: Rüdiger Herrmann <ruediger.herrmann@gmx.de>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

Sometime the new commit is no allocated onto a new lane leading to
the commit being drawn on the wrong branch and something that looks
like a merge.

The drawback is that this also changes existing valid graphs.

Bug: 368927
Change-Id: Ic8a8247c8a53be802c1be83850ed766b902ca646

JGit allows to create commits which have duplicate parents: e.g. a
commit X has first parent Y and second parent Y. Such commits are not
handled correctly by PlotCommit leading to wrong display of the history
in EGit. In such cases there is a never ending passing line drawn beside
all commits younger than the commit with duplicate parents. This commit
fixes this by explicitly checking for duplicate parents.

In a different commit we should fix JGit not to create commits with
duplicate parents. I think native git also doesn't allow such commits,
although history display in native git (gitk, git log --graph) is not
damaged by such commits.

Change-Id: Ie3019ef613a507023958bea27b1badc3b8950279

Change-Id: I3a5b877efd3a58ad463c47bb663d073baea81dda
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>

Eclipse has some problem re-running single JUnit tests if
the tests are in Junit 3 format, but the JUnit 4 launcher
is used. This was quite unnecessary and the move was not
completed. We still have no JUnit4 test.

This completes the extermination of JUnit3. Most of the
work was global searce/replace using regular expression,
followed by numerous invocarions of quick-fix and organize
imports and verification that we had the same number of
tests before and after.

- Annotations were introduced.
- All references to JUnit3 classes removed
- Half-good replacement for getting the test name. This was
  needed to make the TestRngs work. The initialization of
  TestRngs was also made lazily since we can not longer find
  out the test name in runtime in the @Before methods.
- Renamed test classes to end with Test, with the exception
  of TestTranslateBundle, which fails from Maven
- Moved JGitTestUtil to the junit support bundle

Change-Id: Iddcd3da6ca927a7be773a9c63ebf8bb2147e2d13
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

In PlotCommitList.enter() commits are positioned on lanes for visual
presentation. This implementation was buggy: commits without
children (often the starting points for the RevWalk) are not positioned
on separate lanes.

The problem was that when handling commits with multiple children
(that's where branches fork out) it was not handled that some of the
children may not have been positioned on a lane yet. I fixed that and
added a number of tests which specifically test the layout of commits
on lanes.

Bug: 300282
Bug: 320263
Change-Id: I267b97ecccb5251cec54cec90207e075ab50503e
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>