Disable failing System.IO tests

Author: stephentoub

src/System.IO.FileSystem/tests/Directory/GetDirectoryRoot.cs

@@ -49,6 +49,7 @@ public void WhitespacePaths()
             Assert.Equal(Path.GetPathRoot(Directory.GetCurrentDirectory()), root);
         }
 
+        [ActiveIssue(27552)]
         [Fact]
         [PlatformSpecific(TestPlatforms.Windows)]  // UNC shares
         public void UNCShares()

src/System.IO.FileSystem/tests/Directory/GetParent.cs

@@ -38,6 +38,7 @@ public void DotsInPathAreValid()
             Assert.Equal(TestDirectory, test.FullName);
         }
 
+        [ActiveIssue(27552)]
         [Fact]
         [PlatformSpecific(TestPlatforms.Windows)]  // UNC shares
         public void UNCShares()

src/System.IO.FileSystem/tests/DirectoryInfo/Root.cs

@@ -31,6 +31,7 @@ public void DotsInPathAreValid()
             Assert.Equal(root, test.FullName);
         }
 
+        [ActiveIssue(27552)]
         [Fact]
         [PlatformSpecific(TestPlatforms.Windows)]  // UNC shares
         public void UNCShares()

src/System.IO.FileSystem/tests/FileInfo/Directory.cs

@@ -47,6 +47,7 @@ public void DotsInPathAreValid()
             Assert.Equal(TestDirectory, directory);
         }
 
+        [ActiveIssue(27552)]
         [Fact]
         [PlatformSpecific(TestPlatforms.Windows)]  // UNC shares
         public void UNCShares()

src/System.Runtime.Extensions/tests/System/IO/PathTests_Windows.cs

@@ -39,6 +39,7 @@ public static void GetFileName_Volume(string path, string expected)
             Assert.Equal(expected, Path.GetFileName(path));
         }
 
+        [ActiveIssue(27552)]
         [Theory,
             MemberData(nameof(TestData_GetPathRoot_Windows)),
             MemberData(nameof(TestData_GetPathRoot_Unc)),

src/System.Runtime.Extensions/tests/System/IO/PathTests_Windows.netcoreapp.cs

@@ -8,6 +8,7 @@ namespace System.IO.Tests
 {
     public partial class PathTests_Windows : PathTestsBase
     {
+        [ActiveIssue(27552)]
         [Theory,
             MemberData(nameof(TestData_GetPathRoot_Windows)),
             MemberData(nameof(TestData_GetPathRoot_Unc)),