mergeinfo not inherrited when I thought it should

Hello,

In a quick test, we have a project which has the following structure:

/trunk/project/subfolder/file

Next, we create a branch from /trunk/project to

/branches/project/branch1/

We edit file on trunk a first time, changing line1 and commit

Inside branch1, we do a merge from trunk. This creates mergeinfo on
/branches/project/branch1

We edit file on trunk a second time, reverting line1, changing line2 and commit

Inside branch1/subfolder, we do a merge from trunk/subfolder.

This last step ignores the mergeinfo on /branches/project/branch1/ and
merges all revisions again since we made the branch. I thought
inherrited mergeinfo would be used here to see that a first part of
the revision range did not need to be merged again. However, this does
not happen.

The result is that we merge the combination of the 2 edits, which is
only changing line2.
However, we had already merged the change to line1, so the revert on
line1 should have been merged too.

See attachment for a reproduction scenario.

Is this scenario supposed to be handled by SVN ?
We are in a corporate environment, using 1.5.1. Is the above scenario
known to be handled correctly in later versions?
Is it a known issue?
Do I try something which is not supported by SVN?

Kind regards,

Pieter-Jan Busschaert