[GRASS5] do polylines share endpoints?

I am trying to use v.select on a stream layer to select all stream
segments connected to a chosen segment, first using v.extract:

v.extract list=96 input=streams output=foo

then using v.select with "foo":

v.select ainput=streams binput=foo output=bar

This works fine for most segments, but many segments that are clearly
attached to other segments are considered by v.select to be unattached.
For example, in the screen shot I have attached to this message, the red
line shows the layer "bar" which by the method above should be that
segment *plus* the 2 segments to which it is clearly connected. Shouldnt
these three segments share an endpoint? If not, how is one supposed to
select neighbours?

Thanks for any clarification,
Chris

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