Merge branch 'mh/rebase-fixup' (early part)

* 'mh/rebase-fixup' (early part):
  rebase-i: Ignore comments and blank lines in peek_next_command
  lib-rebase: Allow comments and blank lines to be added to the rebase script
  lib-rebase: Provide clearer debugging info about what the editor did
  Add a command "fixup" to rebase --interactive
  t3404: Use test_commit to set up test repository

diff --combined git-rebase--interactive.sh
index 1560e84bd5d06345dd3976ed55c1cfb8af51b41e,55c451ade4aeb4edd09faeaa16d94353707a23fb..d0b59c96c4cba1cd645f834818b5d613ca059ca3
--- 1/git-rebase--interactive.sh
--- 2/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@@ -302,7 -302,10 +302,10 @@@ nth_string () 
  
  make_squash_message () {
        if test -f "$SQUASH_MSG"; then
-               COUNT=$(($(sed -n "s/^# This is [^0-9]*\([1-9][0-9]*\).*/\1/p" \
+               # We want to be careful about matching only the commit
+               # message comment lines generated by this function.
+               # "[snrt][tdh]" matches the nth_string endings.
+               COUNT=$(($(sed -n "s/^# Th[^0-9]*\([1-9][0-9]*\)[snrt][tdh] commit message.*:/\1/p" \
                        < "$SQUASH_MSG" | sed -ne '$p')+1))
                echo "# This is a combination of $COUNT commits."
                sed -e 1d -e '2,/^./{
@@@ -315,10 -318,23 +318,23 @@@
                echo
                git cat-file commit HEAD | sed -e '1,/^$/d'
        fi
-       echo
-       echo "# This is the $(nth_string $COUNT) commit message:"
-       echo
-       git cat-file commit $1 | sed -e '1,/^$/d'
+       case $1 in
+       squash)
+               echo
+               echo "# This is the $(nth_string $COUNT) commit message:"
+               echo
+               git cat-file commit $2 | sed -e '1,/^$/d'
+               ;;
+       fixup)
+               echo
+               echo "# The $(nth_string $COUNT) commit message will be skipped:"
+               echo
+               # Comment the lines of the commit message out using
+               # "#    " rather than "# " to make them less likely to
+               # confuse the sed regexp above.
+               git cat-file commit $2 | sed -e '1,/^$/d' -e 's/^/#     /'
+               ;;
+       esac
  }
  
  peek_next_command () {
@@@ -367,20 -383,28 +383,28 @@@ do_next () 
                warn
                exit 0
                ;;
-       squash|s)
-               comment_for_reflog squash
+       squash|s|fixup|f)
+               case "$command" in
+               squash|s)
+                       squash_style=squash
+                       ;;
+               fixup|f)
+                       squash_style=fixup
+                       ;;
+               esac
+               comment_for_reflog $squash_style
  
                test -f "$DONE" && has_action "$DONE" ||
-                       die "Cannot 'squash' without a previous commit"
+                       die "Cannot '$squash_style' without a previous commit"
  
                mark_action_done
-               make_squash_message $sha1 > "$MSG"
+               make_squash_message $squash_style $sha1 > "$MSG"
                failed=f
                author_script=$(get_author_ident_from_commit HEAD)
                output git reset --soft HEAD^
                pick_one -n $sha1 || failed=t
                case "$(peek_next_command)" in
-               squash|s)
+               squash|s|fixup|f)
                        USE_OUTPUT=output
                        MSG_OPT=-F
                        EDIT_OR_FILE="$MSG"
@@@ -495,25 -519,6 +519,25 @@@ get_saved_options () 
        test -f "$DOTEST"/rebase-root && REBASE_ROOT=t
  }
  
 +LF='
 +'
 +parse_onto () {
 +      case "$1" in
 +      *...*)
 +              if      left=${1%...*} right=${1#*...} &&
 +                      onto=$(git merge-base --all ${left:-HEAD} ${right:-HEAD})
 +              then
 +                      case "$onto" in
 +                      ?*"$LF"?* | '')
 +                              exit 1 ;;
 +                      esac
 +                      echo "$onto"
 +                      exit 0
 +              fi
 +      esac
 +      git rev-parse --verify "$1^0"
 +}
 +
  while test $# != 0
  do
        case "$1" in
@@@ -621,7 -626,7 +645,7 @@@ first and then run 'git rebase --contin
                ;;
        --onto)
                shift
 -              ONTO=$(git rev-parse --verify "$1") ||
 +              ONTO=$(parse_onto "$1") ||
                        die "Does not point to a valid commit: $1"
                ;;
        --)
@@@ -787,6 -792,7 +811,7 @@@
  #  r, reword = use commit, but edit the commit message
  #  e, edit = use commit, but stop for amending
  #  s, squash = use commit, but meld into previous commit
+ #  f, fixup = like "squash", but discard this commit's log message
  #
  # If you remove a line here THAT COMMIT WILL BE LOST.
  # However, if you remove everything, the rebase will be aborted.
@@@ -798,7 -804,7 +823,7 @@@ EO
  
                cp "$TODO" "$TODO".backup
                git_editor "$TODO" ||
 -                      die "Could not execute editor"
 +                      die_abort "Could not execute editor"
  
                has_action "$TODO" ||
                        die_abort "Nothing to do"