bug? find_branches or find_bzrdir tries to open all files as bzr locations

[Alexander Belchenko]

I think this is genuine bug in bzrdir search algorithm or maybe in
find_branches code, but: the latter tries to open every directory and
*every* plain file as bzrdir object. I suppose the original intent was
open_bzrdir always search directories upwards, but find_branches have
to search downwards but it never take care about skipping plain files.

This can be seen with bzr-svn plugin installed because it reports
about every failed attempt to open location as svn tree, see for
example attachment for recent bug
https://bugs.launchpad.net/bugs/778318/+attachment/2116045/+files/.bzr.log

Is it really bug as I think or bzrdir name does not implies it should
be dir only and should support files too? Do you think it should skip
files and check directories only? Dp ypu think current behavior have
some performance penalties because it doing too much useless work?