Change default diff algorithm to histogram and add tests

The referenced bug showed that JGit produced different merge results
compared to C Git. Unit test was added to reproduce the issue. The
problem can be solved by switching to histogram diff algorithm.

Bug: 331078
Change-Id: I54f30afb3a9fef1dbca365ca5f98f4cc846092e3
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Philipp Thun <philipp.thun@sap.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/merge/MergeAlgorithm.java b/org.eclipse.jgit/src/org/eclipse/jgit/merge/MergeAlgorithm.java
index 62febd62c2..e6688f5bc9 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/merge/MergeAlgorithm.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/merge/MergeAlgorithm.java
@@ -50,24 +50,24 @@ import java.util.List;
 import org.eclipse.jgit.diff.DiffAlgorithm;
 import org.eclipse.jgit.diff.Edit;
 import org.eclipse.jgit.diff.EditList;
-import org.eclipse.jgit.diff.MyersDiff;
+import org.eclipse.jgit.diff.HistogramDiff;
 import org.eclipse.jgit.diff.Sequence;
 import org.eclipse.jgit.diff.SequenceComparator;
 import org.eclipse.jgit.merge.MergeChunk.ConflictState;
 
 /**
  * Provides the merge algorithm which does a three-way merge on content provided
- * as RawText. By default {@link MyersDiff} is used as diff algorithm.
+ * as RawText. By default {@link HistogramDiff} is used as diff algorithm.
  */
 public final class MergeAlgorithm {
 	private final DiffAlgorithm diffAlg;
 
 	/**
-	 * Creates a new MergeAlgorithm which uses {@link MyersDiff} as diff
+	 * Creates a new MergeAlgorithm which uses {@link HistogramDiff} as diff
 	 * algorithm
 	 */
 	public MergeAlgorithm() {
-		this(MyersDiff.INSTANCE);
+		this(new HistogramDiff());
 	}
 
 	/**