incorrectly does not fail like it should.
This ensures we will not incorrectly append the file header at the end.
Based on patch by Zhou Zongyi [zhouzongyi at pset.suntec.net]
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@29311 b3059339-0415-0410-9bf9-f77b7e298cf2