Strange merge problem

A user at work came to me with a strange merge issue and I have been able to reproduce it. This happens with both a 1.8.16 and 1.9.4 Linux CLI client. I usually can resolve these merge issues by deleting superfluous svn:mergeinfo properties in subdirectories and/or by editing the svn:mergeinfo property, but nothing works in this case. Here is some information I captured; the only thing that has been altered is the name of the branches to protect our data. All commands were performed in a fresh checkout of the tip of branchB.

TIA for any help or hints to help resolve this issue.

Alfred

$ svn mergeinfo ^/branches/branchA
    youngest common ancestor
    | last full merge
    | | tip of branch
    | | | repository path

    15542 29501
    | |
       --| |------------ branches/branchA
  ... / /
      \ /
       --| |------------ branches/branchB
              | |
              28907 WC
$ svn pg svn:mergeinfo | grep branchA
/branches/branchA:28000-29203
$ svn pe svn:mergeinfo .
Set new value for property 'svn:mergeinfo' on '.'
$ svn pg svn:mergeinfo | grep branchA
/branches/branchA:15542-29203
$ svn mergeinfo ^/branches/branchA --show-revs=eligible
r15544
r15583
[360 revs deleted]
r20783
r20790
r20801
r29207
r29211
r29279
r29303
r29306
r29398
r29425
r29427
r29479
r29482
r29496
r29500
Received on 2016-07-15 03:38:24 CEST