[PATCH] Write sed script directly into temp file, rather than a variable

When sed uses \n rather than ; as a separator (for BSD sed(1) compat),
it is cleaner to use a file directly, rather than an environment
variable containing \n characters.

This change changes t/t6000 write to sed.script directly and changes
the other tests to remove knowledge of sed.script.

Signed-off-by: Jon Seymour <jon.seymour@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>