Merge branch 'cc/bisect'

* cc/bisect:
bisect: remove "checkout_done" variable used when checking merge bases
bisect: only check merge bases when needed
bisect: test merge base if good rev is not an ancestor of bad rev

diff --combined t/t6030-bisect-porcelain.sh
index 36c9a6965f2b200f712ae5a6ae008ca1ef5007a0,c16311469321f2ed23e936d6448d72ab4b937163..85fa39cf0b80d6e3d12a3894f752b9e094345958
--- 1/t/t6030-bisect-porcelain.sh
--- 2/t/t6030-bisect-porcelain.sh
+++ b/t/t6030-bisect-porcelain.sh
@@@ -2,7 -2,7 +2,7 @@@
  #
  # Copyright (c) 2007 Christian Couder
  #
 -test_description='Tests git-bisect functionality'
 +test_description='Tests git bisect functionality'
  
  exec </dev/null
  
@@@ -23,7 -23,7 +23,7 @@@ add_line_into_file(
      fi
  
      test_tick
 -    git-commit --quiet -m "$MSG" $_file
 +    git commit --quiet -m "$MSG" $_file
  }
  
  HASH1=
@@@ -350,6 -350,120 +350,120 @@@ test_expect_success 'bisect does not cr
        git branch -D bisect
  '
  
+ # This creates a "side" branch to test "siblings" cases.
+ #
+ # H1-H2-H3-H4-H5-H6-H7  <--other
+ #            \
+ #             S5-S6-S7  <--side
+ #
+ test_expect_success 'side branch creation' '
+       git bisect reset &&
+       git checkout -b side $HASH4 &&
+       add_line_into_file "5(side): first line on a side branch" hello2 &&
+       SIDE_HASH5=$(git rev-parse --verify HEAD) &&
+       add_line_into_file "6(side): second line on a side branch" hello2 &&
+       SIDE_HASH6=$(git rev-parse --verify HEAD) &&
+       add_line_into_file "7(side): third line on a side branch" hello2 &&
+       SIDE_HASH7=$(git rev-parse --verify HEAD)
+ '
+ 
+ test_expect_success 'good merge base when good and bad are siblings' '
+       git bisect start "$HASH7" "$SIDE_HASH7" > my_bisect_log.txt &&
+       grep "merge base must be tested" my_bisect_log.txt &&
+       grep $HASH4 my_bisect_log.txt &&
+       git bisect good > my_bisect_log.txt &&
+       test_must_fail grep "merge base must be tested" my_bisect_log.txt &&
+       grep $HASH6 my_bisect_log.txt &&
+       git bisect reset
+ '
+ test_expect_success 'skipped merge base when good and bad are siblings' '
+       git bisect start "$SIDE_HASH7" "$HASH7" > my_bisect_log.txt &&
+       grep "merge base must be tested" my_bisect_log.txt &&
+       grep $HASH4 my_bisect_log.txt &&
+       git bisect skip > my_bisect_log.txt 2>&1 &&
+       grep "Warning" my_bisect_log.txt &&
+       grep $SIDE_HASH6 my_bisect_log.txt &&
+       git bisect reset
+ '
+ 
+ test_expect_success 'bad merge base when good and bad are siblings' '
+       git bisect start "$HASH7" HEAD > my_bisect_log.txt &&
+       grep "merge base must be tested" my_bisect_log.txt &&
+       grep $HASH4 my_bisect_log.txt &&
+       test_must_fail git bisect bad > my_bisect_log.txt 2>&1 &&
+       grep "merge base $HASH4 is bad" my_bisect_log.txt &&
+       grep "fixed between $HASH4 and \[$SIDE_HASH7\]" my_bisect_log.txt &&
+       git bisect reset
+ '
+ 
+ # This creates a few more commits (A and B) to test "siblings" cases
+ # when a good and a bad rev have many merge bases.
+ #
+ # We should have the following:
+ #
+ # H1-H2-H3-H4-H5-H6-H7
+ #            \  \     \
+ #             S5-A     \
+ #              \        \
+ #               S6-S7----B
+ #
+ # And there A and B have 2 merge bases (S5 and H5) that should be
+ # reported by "git merge-base --all A B".
+ #
+ test_expect_success 'many merge bases creation' '
+       git checkout "$SIDE_HASH5" &&
+       git merge -m "merge HASH5 and SIDE_HASH5" "$HASH5" &&
+       A_HASH=$(git rev-parse --verify HEAD) &&
+       git checkout side &&
+       git merge -m "merge HASH7 and SIDE_HASH7" "$HASH7" &&
+       B_HASH=$(git rev-parse --verify HEAD) &&
+       git merge-base --all "$A_HASH" "$B_HASH" > merge_bases.txt &&
+       test $(wc -l < merge_bases.txt) = "2" &&
+       grep "$HASH5" merge_bases.txt &&
+       grep "$SIDE_HASH5" merge_bases.txt
+ '
+ 
+ test_expect_success 'good merge bases when good and bad are siblings' '
+       git bisect start "$B_HASH" "$A_HASH" > my_bisect_log.txt &&
+       grep "merge base must be tested" my_bisect_log.txt &&
+       git bisect good > my_bisect_log2.txt &&
+       grep "merge base must be tested" my_bisect_log2.txt &&
+       {
+               {
+                       grep "$SIDE_HASH5" my_bisect_log.txt &&
+                       grep "$HASH5" my_bisect_log2.txt
+               } || {
+                       grep "$SIDE_HASH5" my_bisect_log2.txt &&
+                       grep "$HASH5" my_bisect_log.txt
+               }
+       } &&
+       git bisect reset
+ '
+ 
+ check_trace() {
+       grep "$1" "$GIT_TRACE" | grep "\^$2" | grep "$3" >/dev/null
+ }
+ 
+ test_expect_success 'optimized merge base checks' '
+       GIT_TRACE="$(pwd)/trace.log" &&
+       export GIT_TRACE &&
+       git bisect start "$HASH7" "$SIDE_HASH7" > my_bisect_log.txt &&
+       grep "merge base must be tested" my_bisect_log.txt &&
+       grep "$HASH4" my_bisect_log.txt &&
+       check_trace "rev-list" "$HASH7" "$SIDE_HASH7" &&
+       git bisect good > my_bisect_log2.txt &&
+       test -f ".git/BISECT_ANCESTORS_OK" &&
+       test "$HASH6" = $(git rev-parse --verify HEAD) &&
+       : > "$GIT_TRACE" &&
+       git bisect bad > my_bisect_log3.txt &&
+       test_must_fail check_trace "rev-list" "$HASH6" "$SIDE_HASH7" &&
+       git bisect good "$A_HASH" > my_bisect_log4.txt &&
+       grep "merge base must be tested" my_bisect_log4.txt &&
+       test_must_fail test -f ".git/BISECT_ANCESTORS_OK" &&
+       check_trace "rev-list" "$HASH6" "$A_HASH" &&
+       unset GIT_TRACE
+ '
+ 
  #
  #
  test_done