Test case and comment fixes #760.

The actual fix was introduced in 6d5d641dd7.

ivy/src/main/scala/sbt/Ivy.scala

@@ -314,6 +314,7 @@ private object IvySbt
 	// the common case is for resolved.getArtifactResolver to be inter-project from a different project's publish-local
 	// if there are problems with this, a less aggressive fix might be to only reset the artifact resolver when it is a ProjectResolver
 	// a possible problem is that fetching artifacts is slower, due to the full chain being the artifact resolver instead of the specific resolver
+	// This also fixes #760, which occurs when metadata exists in a repository, but the artifact doesn't.
 	private[this] def resetArtifactResolver(resolved: ResolvedModuleRevision): ResolvedModuleRevision =
 		if(resolved eq null)
 			null

sbt/src/sbt-test/dependency-management/metadata-only-resolver/build.sbt

@@ -0,0 +1,6 @@
+ivyPaths <<= (baseDirectory, target)( (dir, t) => new IvyPaths(dir, Some(t / ".ivy2")))
+
+// not in the default repositories
+libraryDependencies += "com.sun.jmx" % "jmxri" % "1.2.1"
+
+autoScalaLibrary := false

sbt/src/sbt-test/dependency-management/metadata-only-resolver/test

@@ -0,0 +1,6 @@
+# should fail because the dependency is not in the default repositories
+-> update
+
+# add a repository with the dependency, which should then succeed
+> 'set resolvers += "Nuxeo" at "http://maven.nuxeo.org/nexus/content/groups/public/"'
+> update