branch format 6 identifier changed?

[Sabin Iacob]

bzr: ERROR: Unknown branch format: 'Bazaar-NG branch format 6\n'

it looks like the identifier for branch format 6 has changed to "Bazaar 
Branch Format 6 (bzr 0.15)", while .bzr/branch/format contains 
"Bazaar-NG branch format 6"; manually editing the file did the trick 
this time.

my question is, is this format going to be dropped? and if so, will 
there be an alternative that supports tags?