title: Strict conflict resolution in sbt finds strange conflicts
body: <p>I have a big sbt project, and we use strict conflict resolution, so we have to put in a lot of overrides.</p>
  
  <p>Among the more puzzling conflicts we get are these:</p>
  
  <p><code>com.fasterxml.jackson.core#jackson-databind;2.1.1 (needed by [com.amazonaws#aws-java-sdk;1.8.9.1]) conflicts with com.fasterxml.jackson.core#jackson-databind;2.2.2 (needed by [])</code></p>
  
  <p>Version 2.2.2 is needed by nothing?</p>
  
  <p>Another one is this one:</p>
  
  <p><code>commons-logging#commons-logging;1.1.3 (needed by
  [org.apache.httpcomponents#httpclient;4.3.1,
  com.amazonaws#aws-java-sdk;1.8.9.1]) conflicts with
  commons-logging#commons-logging;1.1.1 (needed by
  [com.amazonaws#aws-java-sdk;1.8.9.1])</code></p>
  
  <p>The same package (aws-java-sdk 1.8.9.1) needs two different versions of commons-logging.</p>
  
  <p>I can easily get around these by putting in more overrides, but it shakes my trust in the conflict resolver. Are these messages harmful? How do I get rid of them without putting in overrides?</p>