pager: remove 'S' from $LESS by default

By default, Git used to set $LESS to -FRSX if $LESS was not set by
the user. The FRX flags actually make sense for Git (F and X because
sometimes the output Git pipes to less is short, and R because Git
pipes colored output). The S flag (chop long lines), on the other
hand, is not related to Git and is a matter of user preference. Git
should not decide for the user to change LESS's default.

More specifically, the S flag harms users who review untrusted code
within a pager, since a patch looking like:

    -old code;
    +new good code; [... lots of tabs ...] malicious code;

would appear identical to:

    -old code;
    +new good code;

Users who prefer the old behavior can still set the $LESS environment
variable to -FRSX explicitly, or set core.pager to 'less -S'.

The documentation in config.txt is made a bit longer to keep both an
example setting the 'S' flag (needed to recover the old behavior)
and an example showing how to unset a flag set by Git.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/pager.c b/pager.c
index 0cc75a8..f75e8ae 100644
--- a/pager.c
+++ b/pager.c
@@ -85,7 +85,7 @@ void setup_pager(void)
 		int i = 0;
 
 		if (!getenv("LESS"))
-			env[i++] = "LESS=FRSX";
+			env[i++] = "LESS=FRX";
 		if (!getenv("LV"))
 			env[i++] = "LV=-c";
 		env[i] = NULL;