Rar2 fix with new unit tests that fail on previous build.

src/SharpCompress/Common/Rar/RarEntry.cs

@@ -10,7 +10,7 @@ namespace SharpCompress.Common.Rar
         /// <summary>
         /// As the V2017 port isn't complete, add this check to use the legacy Rar code.
         /// </summary>
-        internal bool IsRarV3 => FileHeader.CompressionAlgorithm == 29 || FileHeader.CompressionAlgorithm == 36;
+        internal bool IsRarV3 => FileHeader.CompressionAlgorithm == 20 || FileHeader.CompressionAlgorithm == 26 || FileHeader.CompressionAlgorithm == 29 || FileHeader.CompressionAlgorithm == 36; //Nanook - Added 20+26 as Test arc from WinRar2.8 (algo 20) was failing with 2017 code
 
         /// <summary>
         /// The File's 32 bit CRC Hash

tests/SharpCompress.Test/Rar/RarArchiveTests.cs

@@ -360,6 +360,31 @@ namespace SharpCompress.Test.Rar
             ArchiveFileRead("Rar5.solid.rar");
         }
 
+        [Fact]
+        public void Rar2_Multi_ArchiveStreamRead()
+        {
+            DoRar_Multi_ArchiveStreamRead(new string[] {
+                "Rar2.multi.rar",
+                "Rar2.multi.r00",
+                "Rar2.multi.r01",
+                "Rar2.multi.r02",
+                "Rar2.multi.r03",
+                "Rar2.multi.r04",
+                "Rar2.multi.r05"}, false);
+        }
+
+        [Fact]
+        public void Rar2_Multi_ArchiveFileRead()
+        {
+            ArchiveFileRead("Rar2.multi.rar"); //r00, r01...
+        }
+
+        [Fact]
+        public void Rar2_ArchiveFileRead()
+        {
+            ArchiveFileRead("Rar2.rar");
+        }
+
         [Fact]
         public void Rar_Multi_ArchiveFileRead()
         {