work around python bug on solaris 10.

write to file opened mode 'a+' should write to end of file and update
offset pointer, but does not (solaris 10 has python 2.3.3).
fix is to always seek.

mercurial/appendfile.py

@@ -70,6 +70,7 b' class appendfile(object):'
 
     def write(self, s):
         '''append to temp file.'''
+        self.tmpfp.seek(0, 2)
         self.tmpfp.write(s)
         # all writes are appends, so offset must go to end of file.
         self.offset = self.fpsize + self.tmpfp.tell()