In your regex [^/]+{0,1} does not make sense if I understand it correctly, basically you say
anything but a slash, at least one time, then you say at least 0 time at most 1... you gotta choose which you want, either it is

[^/]+ or
[^/]? (equivalent to {0,1})
For what you want to do I'd say:
m#\A/usr/([^/]+/)?bin#
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