Make util.find_exe alway returns existing file, fixing issue1459 It seems like the old behaviour with different handling for commands with and without path was intended, but I think this behaviour of util.find_exe is better: * Always returns existing file * or None if command not found - no default * Windows: Returned file thus always ends with extension from PATHEXT This fixes http://www.selenic.com/mercurial/bts/issue1459. The change might fix other unintended behaviour too.