Fix version_negotiation_test timing out.

sdk/lib/_internal/pub/lib/src/solver/dependency_queue.dart

Index: sdk/lib/_internal/pub/lib/src/solver/dependency_queue.dart
diff --git a/sdk/lib/_internal/pub/lib/src/solver/dependency_queue.dart b/sdk/lib/_internal/pub/lib/src/solver/dependency_queue.dart
index c462120575050fbbd1c10ad7c171cb02e1ea51bc..42ca2992daf9380342662058dd87802a6e7ae8a1 100644
--- a/sdk/lib/_internal/pub/lib/src/solver/dependency_queue.dart
+++ b/sdk/lib/_internal/pub/lib/src/solver/dependency_queue.dart
@@ -125,18 +125,9 @@ class DependencyQueue {
   /// versions available for it.
   Future<int> _getNumVersions(PackageDep dep) {
     // There is only ever one version of the root package.
-    if (dep.isRoot) {
-      return new Future.value(1);
-    }
+    if (dep.isRoot) return new Future.value(1);
 
-    return _solver.cache.getVersions(dep.toRef()).then((versions) {
-      return versions.length;
-    }).catchError((error, trace) {
-      // If it fails for any reason, just treat that as no versions. This
-      // will sort this reference higher so that we can traverse into it
-      // and report the error more properly.
-      log.solver("Could not get versions for $dep:\n$error\n\n$trace");
-      return 0;
-    });
+    return _solver.cache.getVersions(dep.toRef())
+        .then((versions) => versions.length);
   }
 }