Re: [PATCH] Don't use $author_name undefined when $from contains no /\s</.

Junio C Hamano [off-list ref] writes:

I see no good reason, other than saving a single byte from the
output stream perhaps.

That wasn't the motivation.  Rather, it was to support the
style where people use editors that highlight trailing
blanks, since trailing blanks can cause trouble in some
contexts (e.g., they can change the semantics of C programs
and Makefiles).  When examining unified diffs, any added or
removed trailing blanks will be easy to spot with such an
editor, but only if "diff -u" doesn't output any trailing
blanks of its own.

You can read more about this at the thread that inspired
the diffutils change, rooted here:

http://lists.gnu.org/archive/html/bug-gnu-utils/2006-09/msg00005.html

Does that mean if you have a line that has only one TAB (perhaps
caused by broken autoindent in the editor), that is "input data"
and is output as "SP TAB LF"?

Yes, that's correct.  In the highlighting-editor scenario,
such a line would be highlighted, but the people who want to
see trailing white space highlighted will indeed want the
highlighting here, so it's fine.

This change was not motivated by broken MUAs.  Broken MUAs
are a problem that GNU 'patch' has already had to deal with,
for many years.  The change was motivated by a desire to
make significant trailing white space easier to find, when
people are examining text that contains some diffs and some
other stuff.