Add Fixes Chris Suggested

Author: Justin Kotalik

src/Microsoft.AspNetCore.Http.Abstractions/PathString.cs

@@ -213,7 +213,7 @@ public string Add(QueryString other)
         /// <returns>True if both PathString values are equal</returns>
         public bool Equals(PathString other)
         {
-            return this.Equals(other, StringComparison.OrdinalIgnoreCase);
+            return Equals(other, StringComparison.OrdinalIgnoreCase);
         }
 
         /// <summary>
@@ -240,7 +240,7 @@ public override bool Equals(object obj)
         {
             if (ReferenceEquals(null, obj))
             {
-                return false;
+                return !HasValue;
             }
             return obj is PathString && Equals((PathString)obj);
         }

test/Microsoft.AspNetCore.Http.Abstractions.Tests/PathStringTests.cs

@@ -21,6 +21,11 @@ public void Equals_EmptyPathStringAndDefaultPathString()
         {
             // Act and Assert
             Assert.Equal(PathString.Empty, default(PathString));
+            Assert.Equal(default(PathString), PathString.Empty);
+            Assert.True(PathString.Empty == default(PathString));
+            Assert.True(default(PathString) == PathString.Empty);
+            Assert.True(PathString.Empty.Equals(default(PathString)));
+            Assert.True(default(PathString).Equals(PathString.Empty));
         }
 
         [Fact]