JGit log strange behavior after merge - git-merge

Question

Found a strange behavior (bug?) in a log command.
The below test creates a repo, creates a branch, does some commits either to the created branch and to master, then merges master to the created branch. After merge it tries to calculate the number of commits between the branch and master. Because master has been already merged -- the branch is not behind the master, i.e. corresponding commit count should be 0.
public class JGitBugTest {
#Rule
public TemporaryFolder tempFolder = new TemporaryFolder();
#Test
public void testJGitLogBug() throws Exception {
final String BRANCH_NAME = "TST-2";
final String MASTER_BRANCH_NAME = Constants.MASTER;
File folder = tempFolder.newFolder();
// Create a Git repository
Git api = Git.init().setBare( false ).setDirectory( folder ).call();
Repository repository = api.getRepository();
// Add an initial commit
api.commit().setMessage( "Initial commit" ).call();
// Create a new branch and add some commits to it
api.checkout().setCreateBranch( true ).setName( BRANCH_NAME ).call();
api.commit().setMessage( "TST-2 Added files 1" ).call();
// Add some commits to master branch too
api.checkout().setName( MASTER_BRANCH_NAME ).call();
api.commit().setMessage( "TST-1 Added files 1" ).call();
api.commit().setMessage( "TST-1 Added files 2" ).call();
// If this delay is commented out -- test fails and
// 'behind' is equal to "the number of commits to master - 1".
// Thread.sleep(1000);
// Checkout the branch and merge master to it
api.checkout().setName( BRANCH_NAME ).call();
api.merge()
.include( repository.resolve( MASTER_BRANCH_NAME ) )
.setStrategy( MergeStrategy.RECURSIVE )
.call()
.getNewHead()
.name();
// Calculate the number of commits the branch behind of the master
// It should be zero because we have merged master into the branch already.
Iterable<RevCommit> iterable = api.log()
.add( repository.resolve( MASTER_BRANCH_NAME ) )
.not( repository.resolve( BRANCH_NAME ) )
.call();
int behind = 0;
for( RevCommit commit : iterable ) {
behind++;
}
Assert.assertEquals( 0, behind );
}
}
The above test fails, behind yields the number of commits in the master minus 1.
Moreover, if 'sleep' in line 43 is uncommented -- the bug will go away, and 'behind' is equal to 0.
What do I do wrong? Is it a bug in JGit library or in my code?

Answer 1

Running the code on Windows, I can reproduce what you describe.
This looks like a bug in JGit to me. I recommend to open a bugzilla or post your findings to the mailing list.