Duplicate trace annotations when L5D-Sample header set

[klingerf]

I've running linkerd with an http router configured to route requests received on port 4140 to a "web" service running on port 7000. When I make a request with the L5D-Sample: 1 header set, I see duplicate trace annotations as follows:

$ curl -H 'Host: web' -H 'L5d-sample: 1' http:https://127.1:4140/ping
...
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 ServiceName(0.0.0.0/4140)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 BinaryAnnotation(srv/finagle.version,6.31.0)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 ServerRecv()
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 LocalAddr(/127.0.0.1:4140)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 ServerAddr(/127.0.0.1:4140)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 ClientAddr(/127.0.0.1:49600)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 BinaryAnnotation(namer.dtab.base,/status=>/$/io.l5d.http.status;/www=>/host/web;/host=>/$/io.buoyant.http.anyHostPfx/www;/host=>/io.l5d.fs;/method=>/$/io.buoyant.http.anyMethodPfx/host;/http/1.1=>/method)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 BinaryAnnotation(namer.dtab.local,)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 BinaryAnnotation(namer.path,/http/1.1/GET/web)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 Message(namer.success)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ServiceName(io.l5d.fs/web)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 BinaryAnnotation(dst.id,/io.l5d.fs/web)
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 BinaryAnnotation(dst.path,/)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ServiceName(io.l5d.fs/web)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(clnt/finagle.version,6.31.0)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(clnt/finagle.version,6.31.0)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ClientSend()
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ClientSend()
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.method,GET)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.method,GET)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.uri,/ping)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.uri,/ping)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.host,web)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.host,web)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.version,HTTP/1.1)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.version,HTTP/1.1)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 WireSend
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 WireSend
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ServerAddr(/127.0.0.1:7000)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ServerAddr(/127.0.0.1:7000)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ClientAddr(/127.0.0.1:49588)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ClientAddr(/127.0.0.1:49588)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 WireRecv
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 WireRecv
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.status,200)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.status,200)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.version,HTTP/1.1)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.version,HTTP/1.1)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.content-length,4)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.content-length,4)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.content-type,text/plain)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 BinaryAnnotation(http.content-type,text/plain)
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ClientRecv()
bc2f33bcda4be209.fcca4401059c9b52<:bc2f33bcda4be209 ClientRecv()
bc2f33bcda4be209.bc2f33bcda4be209<:bc2f33bcda4be209 ServerSend()