sequencer: remove unnecessary variable setting

revs.pretty_given is only ever read in builtin/log.c, and nothing from
builtin/log.c is ever called from sequencer.c.  So setting this variable
cannot do anything.

This was introduced in commit 62db524 ("rebase -i: generate the
script via rebase--helper", 2017-07-14), which, although `git rev-list`
was in use at the time the commit message talks about how the logic had
been based on `git log`.  Because of this, I am guessing this line was
copied or ported from part of builtin/log.c without recognizing that
this line was not doing anything and could be removed.

It's certainly not doing anything now, though, so remove it.

Signed-off-by: Elijah Newren <newren@gmail.com>

Author: newren

sequencer.c

@@ -6086,7 +6086,6 @@ int sequencer_make_script(struct repository *r, struct strbuf *out, int argc,
 	revs.sort_order = REV_SORT_IN_GRAPH_ORDER;
 	revs.topo_order = 1;
 
-	revs.pretty_given = 1;
 	git_config_get_string("rebase.instructionFormat", &format);
 	if (!format || !*format) {
 		free(format);