Add comment about this test failing under bzr 1.13 due to a bug in bzr.

tests/test-convert-bzr-merges

@@ -1,39 +1,43 b''
 #!/bin/sh
 
+# N.B. bzr 1.13 has a bug that breaks this test.  If you see this
+# test fail, check your bzr version.  Upgrading to bzr 1.13.1
+# should fix it.
+
 . "$TESTDIR/bzr-definitions"
 
 echo % test multiple merges at once
 mkdir test-multimerge
 cd test-multimerge
 bzr init -q source
 cd source
 echo content > file
 bzr add -q file
 bzr commit -q -m 'Initial add'
 cd ..
 bzr branch -q source source-branch1
 cd source-branch1
 echo morecontent >> file
 echo evenmorecontent > file-branch1
 bzr add -q file-branch1
 bzr commit -q -m 'Added branch1 file'
 cd ../source
 sleep 1
 echo content > file-parent
 bzr add -q file-parent
 bzr commit -q -m 'Added parent file'
 cd ..
 bzr branch -q source source-branch2
 cd source-branch2
 echo somecontent > file-branch2
 bzr add -q file-branch2
 bzr commit -q -m 'Added brach2 file'
 sleep 1
 cd ../source
 bzr merge -q ../source-branch1
 bzr merge -q --force ../source-branch2
 bzr commit -q -m 'Merged branches'
 cd ..
 hg convert --datesort source source-hg
 glog -R source-hg
 manifest source-hg tip