Since the very beginning of Git, we gave the LESS environment a
default value "FRSX" when we spawn "less" as the pager. "S" (chop
long lines instead of wrapping) has been removed from this default
set of options, because it is more or less a personal taste thing,
as opposed to others that have good justifications (i.e. "R" is very
much justified because many kinds of output we produce are colored
and "FX" is justified because output we produce is often shorter
than a page).
Existing users who prefer not to see line-wrapped output may want to
$ git config core.pager "less -S"
to restore the traditional behaviour. It is expected that people
find output from the most subcommands easier to read with the new
default, except for "blame" which tends to produce really long
lines. To override the new default only for "git blame", you can do
$ git config pager.blame "less -S"
pager: remove 'S' from $LESS by default