Don't return duplicated artifacts from Ivy repos

appveyor.yml

@@ -22,7 +22,7 @@ install:
         Set-Location -Path ..
       }
 build_script:
-  - sbt ++2.11.11 clean compile coreJVM/publishLocal
+  - sbt ++2.11.11 clean compile coreJVM/publishLocal cli/publishLocal
   - sbt ++2.12.1 http-server/publishLocal
   - sbt ++2.10.6 clean compile
   - sbt ++2.12.1 coreJVM/publishLocal cache/publishLocal extra/publishLocal # to make the scripted sbt 1.0 tests happy

core/shared/src/main/scala/coursier/ivy/IvyRepository.scala

@@ -88,7 +88,7 @@ final case class IvyRepository(
                 }
             }
 
-          val retainedWithUrl = retained.flatMap { p =>
+          val retainedWithUrl = retained.distinct.flatMap { p =>
             pattern.substituteVariables(variables(
               dependency.module,
               Some(project.actualVersion),

scripts/travis.sh

@@ -30,7 +30,7 @@ launchProxyRepos() {
 
 integrationTestsRequirements() {
   # Required for ~/.ivy2/local repo tests
-  sbt ++2.11.11 coreJVM/publishLocal
+  sbt ++2.11.11 coreJVM/publishLocal cli/publishLocal
 
   sbt ++2.12.1 http-server/publishLocal
 

tests/jvm/src/it/scala/coursier/test/IvyLocalTests.scala

@@ -17,13 +17,30 @@ object IvyLocalTests extends TestSuite {
       val extraRepo = Some(Cache.ivy2Local)
 
       // Assuming this module (and the sub-projects it depends on) is published locally
-      * - CentralTests.resolutionCheck(
+      'resolution - CentralTests.resolutionCheck(
         module, version,
         extraRepo
       )
 
+      'uniqueArtifacts - async {
 
-      * - async {
+        val res = await(CentralTests.resolve(
+          Set(Dependency(Module("io.get-coursier", "coursier-cli_2.11"), version, transitive = false)),
+          extraRepo = extraRepo
+        ))
+
+        val artifacts = res.dependencyClassifiersArtifacts(Seq("standalone"))
+          .map(_._2)
+          .filter(a => a.`type` == "jar" && !a.isOptional)
+          .map(_.url)
+          .groupBy(s => s)
+
+        assert(artifacts.nonEmpty)
+        assert(artifacts.forall(_._2.length == 1))
+      }
+
+
+      'javadocSources - async {
         val res = await(CentralTests.resolve(
           Set(Dependency(module, version)),
           extraRepo = extraRepo