Before we asserted on unique lane indications per lane. Turns out the
OSM data contains lane strings such as:
left;left|right
Which represents two lanes as in:
<< >
|| |
The two left indications _on a single lane_ look like data issue.
And we can't represent this with our enum-approach at the moment.
We don't want to crash there, so silently swallow this and
generate a single left|right for it.
