Fix edges disappearing.
Fix edges disappearing.

weaveworks/scope,alban/scope,weaveworks/scope,kinvolk/scope,kinvolk/scope,alban/scope,weaveworks/scope,weaveworks/scope,alban/scope,alban/scope,kinvolk/scope,weaveworks/scope,weaveworks/scope,kinvolk/scope,kinvolk/scope,kinvolk/scope,alban/scope,alban/scope