Temporary hack

to minimize the chance of two different Artifact to have the same URL -
these are handled well by the cache if the corresponding URL has not
been downloaded yet, and result in one download locking the file for the
others

core/shared/src/main/scala/coursier/core/Resolution.scala

@@ -885,7 +885,10 @@ final case class Resolution(
           .getOrElse(Map.empty)
     )
 
-  private def artifacts0(overrideClassifiers: Option[Seq[String]]): Seq[Artifact] = {
+  private def artifacts0(
+    overrideClassifiers: Option[Seq[String]],
+    keepAttributes: Boolean
+  ): Seq[Artifact] = {
     val res = for {
       dep <- minDependencies.toSeq
       (source, proj) <- projectCache
@@ -893,16 +896,19 @@ final case class Resolution(
         .toSeq
       artifact <- source
         .artifacts(dep, proj, overrideClassifiers)
-    } yield artifact
+    } yield (if (keepAttributes) artifact else artifact.copy(attributes = Attributes("", "")))
 
     res.distinct
   }
 
+  // temporary hack :-|
+  // if one wants the attributes field of artifacts not to be cleared, call dependencyArtifacts
+
   def classifiersArtifacts(classifiers: Seq[String]): Seq[Artifact] =
-    artifacts0(Some(classifiers))
+    artifacts0(Some(classifiers), keepAttributes = false)
 
   def artifacts: Seq[Artifact] =
-    artifacts0(None)
+    artifacts0(None, keepAttributes = false)
 
   private def dependencyArtifacts0(overrideClassifiers: Option[Seq[String]]): Seq[(Dependency, Artifact)] =
     for {

plugin/src/main/scala-2.10/coursier/Tasks.scala

@@ -581,9 +581,11 @@ object Tasks {
         }.toSet
 
         def artifactFileOpt(artifact: Artifact) = {
-          val res = artifactFiles.get(artifact)
+          val artifact0 = artifact
+            .copy(attributes = Attributes()) // temporary hack :-(
+          val res = artifactFiles.get(artifact0)
 
-          if (res.isEmpty && !erroredArtifacts(artifact))
+          if (res.isEmpty && !erroredArtifacts(artifact0))
             log.error(s"${artifact.url} not downloaded (should not happen)")
 
           res