add testcase for writing past the end of a file
add testcase for writing past the end of a file

pmitros/pyfs,rivenz/pyfilesystem,PyFilesystem/pyfilesystem,Konubinix/pyfilesystem,piranna/pyfilesystem,pmitros/pyfs,zopyx/pyfilesystem,pombreda/pyfilesystem,flying-circus/pyfilesystem