Sometimes mailers, editors, or other programs change spaces into tabs,
or vice versa. If this happens to a patch file or an input file, the
files might look the same, but patch will not be able to match
them properly. If this problem occurs, use the -l or
--ignore-white-space option, which makes patch compare
blank characters (i.e. spaces and tabs) loosely so that any nonempty
sequence of blanks in the patch file matches any nonempty sequence of
blanks in the input files. Non-blank
characters must still match exactly. Each line of the context must
still match a line in the input file.