System.Reflection.Metadata: preserve pre-linked suffix chain when linking into empty BlobBuilder

src/libraries/System.Reflection.Metadata/src/System/Reflection/Metadata/BlobBuilder.cs

@@ -479,7 +479,12 @@ public void LinkSuffix(BlobBuilder suffix)
             // The value is not used, other than for calculating the value of Count property.
             suffix._previousLengthOrFrozenSuffixLengthDelta = suffixPreviousLength + oldSuffixLength - suffix.Length;
 
-            if (!isEmpty)
+            if (isEmpty)
+            {
+                var suffixLast = suffix._nextOrPrevious;
+                _nextOrPrevious = (suffixLast != suffix) ? suffixLast : this;
+            }
+            else
             {
                 // First and last chunks:
                 //

src/libraries/System.Reflection.Metadata/tests/Metadata/BlobTests.cs

@@ -514,6 +514,48 @@ public void LinkSuffix_Empty3()
             Assert.Equal(16, builder2.Count);
         }
 
+        [Fact]
+        public void LinkSuffix_EmptyDestination_SuffixAlreadyLinked()
+        {
+            var emptyPrefix = new BlobBuilder(16);
+            var element = new BlobBuilder(16);
+            var tail = new BlobBuilder(16);
+
+            element.WriteByte(0x11);
+            tail.WriteByte(0x22);
+
+            element.LinkSuffix(tail);
+            emptyPrefix.LinkSuffix(element);
+
+            AssertEx.Equal(new byte[] { 0x11, 0x22 }, emptyPrefix.ToArray());
+            Assert.Equal(2, emptyPrefix.Count);
+            Assert.Equal(2, element.Count);
+            Assert.Equal(1, tail.Count);
+        }
+
+        [Fact]
+        public void LinkSuffix_EmptyDestination_SuffixThreeChunkChain()
+        {
+            var emptyPrefix = new BlobBuilder(16);
+            var first = new BlobBuilder(16);
+            var second = new BlobBuilder(16);
+            var third = new BlobBuilder(16);
+
+            first.WriteByte(0x11);
+            second.WriteByte(0x22);
+            third.WriteByte(0x33);
+
+            first.LinkSuffix(second);
+            first.LinkSuffix(third);
+            emptyPrefix.LinkSuffix(first);
+
+            AssertEx.Equal(new byte[] { 0x11, 0x22, 0x33 }, emptyPrefix.ToArray());
+            Assert.Equal(3, emptyPrefix.Count);
+            Assert.Equal(3, first.Count);
+            Assert.Equal(1, second.Count);
+            Assert.Equal(1, third.Count);
+        }
+
         [Fact]
         public void LinkPrefix1()
         {