Merge branch 'ah/rebase-no-fork-point-config'

"git rebase --[no-]fork-point" gained a configuration variable
rebase.forkPoint so that users do not have to keep specifying a
non-default setting.

* ah/rebase-no-fork-point-config:
  rebase: add a config option for --no-fork-point

diff --cc t/t3431-rebase-fork-point.sh
index 2dab893c759b288cefeb0d4b35ac4f4eb82b2eae,2d07bd9fd2034aed5bbe474e5246229ed7d9730e..4c98d99e7e87476811877b4685f2f5a5eefe0f35
--- 1/t/t3431-rebase-fork-point.sh
--- 2/t/t3431-rebase-fork-point.sh
+++ b/t/t3431-rebase-fork-point.sh
@@@ -29,6 -26,19 +29,19 @@@ test_expect_success setup 
        test_commit G
  '
  
 -      git checkout master &&
+ do_test_rebase () {
+       expected="$1" &&
+       shift &&
++      git checkout main &&
+       git reset --hard E &&
+       git checkout side &&
+       git reset --hard G &&
+       git rebase $* &&
+       test_write_lines $expected >expect &&
+       git log --pretty=%s >actual &&
+       test_cmp expect actual
+ }
+ 
  test_rebase () {
        expected="$1" &&
        shift &&