I don't see any more problems.
I understand the reason to create a configurable list of bar-types where
the volta bracket hooks.
I do not see any reason to move the decision on whether to draw the hook
from stencil-maker to engraver. The engraver does not yet know where
the line-breaks will be, and the hook looks odd at the end of a line.
http://codereview.appspot.com/6422061/diff/8001/ly/engraver-init.ly
File ly/engraver-init.ly (right):
http://codereview.appspot.com/6422061/diff/8001/ly/engraver-init.ly#newcode622
ly/engraver-init.ly:622: ":|" "|:" "||:" "|." ":|:" ":|.|:" ":|.:" ".|"
trim trailing whitespace before pushing if you remember
http://codereview.appspot.com/6422061/