scope: conntrack errors do not back off

On my machine, I don’t have conntrack installed or conntrack tools enabled or something like that. I get this spammed to my log:

<probe> ERRO: 2016/10/05 23:54:47.433553 conntrack error: EOF
<probe> ERRO: 2016/10/05 23:54:47.433571 conntrack error: exit status 1
<probe> ERRO: 2016/10/05 23:54:48.435064 conntrack existingConnections exit error: exit status 1
<probe> ERRO: 2016/10/05 23:54:48.435953 conntrack existingConnections exit error: exit status 1
<probe> ERRO: 2016/10/05 23:54:48.437096 conntrack error: EOF
<probe> ERRO: 2016/10/05 23:54:48.437119 conntrack error: exit status 1
<probe> ERRO: 2016/10/05 23:54:48.437090 conntrack stderr:conntrack v1.4.3 (conntrack-tools): Can't open handler
<probe> ERRO: 2016/10/05 23:54:48.437134 conntrack stderr:read |0: bad file descriptor
<probe> ERRO: 2016/10/05 23:54:48.437268 conntrack error: EOF
<probe> ERRO: 2016/10/05 23:54:48.437253 conntrack stderr:conntrack v1.4.3 (conntrack-tools): Can't open handler
<probe> ERRO: 2016/10/05 23:54:48.437287 conntrack error: exit status 1
<probe> ERRO: 2016/10/05 23:54:49.439317 conntrack existingConnections exit error: exit status 1
<probe> ERRO: 2016/10/05 23:54:49.440662 conntrack existingConnections exit error: exit status 1
<probe> ERRO: 2016/10/05 23:54:49.441934 conntrack stderr:conntrack v1.4.3 (conntrack-tools): Can't open handler
<probe> ERRO: 2016/10/05 23:54:49.442009 conntrack error: EOF
<probe> ERRO: 2016/10/05 23:54:49.442042 conntrack error: exit status 1
<probe> ERRO: 2016/10/05 23:54:49.444396 conntrack stderr:conntrack v1.4.3 (conntrack-tools): Can't open handler
<probe> ERRO: 2016/10/05 23:54:49.444432 conntrack error: EOF
<probe> ERRO: 2016/10/05 23:54:49.444469 conntrack error: exit status 1
<probe> ERRO: 2016/10/05 23:54:50.443697 conntrack existingConnections exit error: exit status 1
<probe> ERRO: 2016/10/05 23:54:50.445962 conntrack stderr:conntrack v1.4.3 (conntrack-tools): Can't open handler
<probe> ERRO: 2016/10/05 23:54:50.445989 conntrack error: EOF
<probe> ERRO: 2016/10/05 23:54:50.446018 conntrack error: exit status 1
<probe> ERRO: 2016/10/05 23:54:50.446275 conntrack existingConnections exit error: exit status 1

These errors should back off after failure.