Line 317 of Phing.php has a loop over argument keys. When the args are empty, the warning below is issued.
Attached is a patch that resolves the issue by not iterating over an empty argument list.
Aug 27 09:23:00 [warning] max(): Array must contain at least one element (/path/to/pear/phing/Phing.php at line 317)
====backtrace ====
#0 max() called at [/path/to/pear/phing/Phing.php:317] args{Array}
#1 Phing->execute() called at [/path/to/pear/phing/Phing.php:157] args{Array}
#2 Phing::start() called at [/path/to/pear/phing/Phing.php:270] args{Array, }
#3 Phing::fire() called at [/path/to/phingcmd.php:40] args{Array}
