diff --color-moved-ws: demonstrate false positives

diff --color-moved-ws: demonstrate false positives

'diff --color-moved-ws=allow-indentation-change' can highlight lines
that have internal whitespace changes rather than indentation
changes. For example in commit 1a07e59c3e ("Update messages in
preparation for i18n", 2018-07-21) the lines

-               die (_("must end with a color"));
+               die(_("must end with a color"));

are highlighted as moved when they should not be. Modify an existing
test to show the problem that will be fixed in the next commit.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Reviewed-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>