[PackageGraph] Filter unversioned pins before running the debug algo

<rdar://problem/39616386> Crash under BasePackageContainer.versions(filter:)
https://bugs.swift.org/browse/SR-8177

(cherry picked from commit be4bc8c)

Sources/PackageGraph/DependencyResolver.swift

@@ -1332,7 +1332,7 @@ private struct ResolverDebugger<
  /// This algorithm can be exponential, so we abort after the predefined time limit.
  func debug(
  dependencies inputDependencies: [Constraint],
- pins: [Constraint]
+ pins inputPins: [Constraint]
  ) throws -> (dependencies: [Constraint], pins: [Constraint]) {
 
  // Form the dependencies array.
@@ -1353,10 +1353,12 @@ private struct ResolverDebugger<
  }
  }
 
- // Remove the unversioned constraints which may be added as result of the above loop.
- dependencies = dependencies.filter({ dep in
- return !inputDependencies.contains(where: { $0.identifier == dep.identifier && $0.requirement == .unversioned })
- })
+ // Form a set of all unversioned dependencies.
+ let unversionedDependencies = Set(inputDependencies.filter({ $0.requirement == .unversioned }).map({ $0.identifier }))
+
+ // Remove the unversioned constraints from dependencies and pins.
+ dependencies = dependencies.filter({ !unversionedDependencies.contains($0.identifier) })
+ let pins = inputPins.filter({ !unversionedDependencies.contains($0.identifier) })
 
  // Put the resolver in incomplete mode to avoid cloning new repositories.
  resolver.isInIncompleteMode = true

Tests/WorkspaceTests/WorkspaceTests.swift

@@ -1682,12 +1682,15 @@ final class WorkspaceTests: XCTestCase {
  workspace.checkManagedDependencies { result in
  result.check(dependency: "foo", at: .edited(nil))
  }
+ workspace.checkResolved() { result in
+ result.check(dependency: "foo", at: .checkout(.version("1.0.0")))
+ }
 
  // Try resolving a bad graph.
  let deps: [TestWorkspace.PackageDependency] = [
  .init(name: "Bar", requirement: .exact("1.1.0")),
  ]
- workspace.checkUpdate(roots: ["Root"], deps: deps) { diagnostics in
+ workspace.checkPackageGraph(roots: ["Root"], deps: deps) { (_, diagnostics) in
  DiagnosticsEngineTester(diagnostics) { result in
  result.check(diagnostic: .contains("/tmp/ws/pkgs/Bar @ 1.1.0"), behavior: .error)
  }