Support 'whence' parameter to seek().

Lib/multifile.py

@@ -44,8 +44,17 @@ class MultiFile:
 			return self.lastpos
 		return self.fp.tell() - self.start
 	#
-	def seek(self, pos):
-		if not 0 <= pos <= self.tell() or \
+	def seek(self, pos, whence=0):
+                here = self.tell()
+                if whence:
+                        if whence == 1:
+                                pos = pos + here
+                        elif whence == 2:
+                                if self.level > 0:
+                                        pos = pos + self.lastpos
+                                else:
+                                        raise Error, "can't use whence=2 yet"
+		if not 0 <= pos <= here or \
 				self.level > 0 and pos > self.lastpos:
 			raise Error, 'bad MultiFile.seek() call'
 		self.fp.seek(pos + self.start)