Merge branch 'pldg-master'

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# especially if it merges an updated upstream into a topic branch.
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Author: McNeight

ICSharpCode.SharpZipLib/Zip/ZipFile.cs

@@ -3673,8 +3673,11 @@ public override int Read(byte[] buffer, int offset, int count)
 							return 0;
 						}
 					}
-
-					baseStream_.Seek(readPos_, SeekOrigin.Begin);
+					// Protect against Stream implementations that throw away their buffer on every Seek
+					// (for example, Mono FileStream)
+					if (baseStream_.Position != readPos_) {
+						baseStream_.Seek(readPos_, SeekOrigin.Begin);
+					}
 					int readCount = baseStream_.Read(buffer, offset, count);
 					if (readCount > 0) {
 						readPos_ += readCount;