[PATCH v2 0/3] Linux with musl libc improvement

This series of patch tries to ease the life of musl libc user and clear those last failure on Linux with musl libc.

The second patch is a complete rewrite.

Doan Tran Cong Danh (3):
  t0028: eliminate non-standard usage of printf
  configure.ac: define ICONV_OMITS_BOM if necessary
  sequencer: reencode to utf-8 before arrange rebase's todo list

 configure.ac                     | 49 ++++++++++++++++++++++++++++++++
 sequencer.c                      |  2 +-
 t/t0028-working-tree-encoding.sh |  4 +--
 3 files changed, 52 insertions(+), 3 deletions(-)

Range-diff against v1:
1:  840c40cea1 ! 1:  8b30028425 t0028: eliminate non-standard usage of printf
    @@ Commit message
            one, two, or three-digit octal number, shall be written as a byte
            with the numeric value specified by the octal number.
     
    -    printf '\xfe\xff' in an extension of some libc.
    +    printf '\xfe\xff' in an extension of some shell.
    +    Dash, a popular yet simple shell, do not implement this extension.
     
    -    With dash:
    -    $ printf '\xfe\xff' | xxd
    -    00000000: 5c78 6665 5c78 6666                      \xfe\xff
    +    This wasn't caught by most people running the tests, even though
    +    common shells like dash don't handle hex escapes, because their
    +    systems don't trigger the NO_UTF16_BOM prereq. But systems with musl
    +    libc do; when combined with dash, the test fails.
     
    -    Correct its usage.
    +    Correct it.
     
         Signed-off-by: Doan Tran Cong Danh <congdanhqx@gmail.com>
    -    Despite that dash's printf doesn't accept \x escape sequence.
    -
    -    My glibc box (with sh linked to dash) can run the test just fine.
    -    But my musl box couldn't run the test, (because the header).
     
      ## t/t0028-working-tree-encoding.sh ##
     @@ t/t0028-working-tree-encoding.sh: test_lazy_prereq NO_UTF32_BOM '
2:  4a28ee7ef6 < -:  ---------- configure.ac: define ICONV_OMITS_BOM if necessary
-:  ---------- > 2:  7c2c6f0603 configure.ac: define ICONV_OMITS_BOM if necessary
3:  c8da3990e5 ! 3:  b7927b2723 sequencer: reencode to utf-8 before arrange rebase's todo list
    @@ Commit message
     
         Thus, t3900 is failing on Linux with musl libc.
     
    +    This problem wasn't specific to musl libc. On Linux with glibc, this
    +    problem can be observed by:
    +
    +    for encoding in utf-8 iso-8859-1; do
    +            # commit using the encoding
    +            echo $encoding >file && git add file
    +            echo "éñcödèd with $encoding" | iconv -f utf-8 -t $encoding |
    +              git -c i18n.commitEncoding=$encoding commit -F -
    +            # and then fixup without it
    +            echo "$encoding fixed" >file && git add file
    +            git commit --fixup HEAD
    +    done
    +    git rebase -i --autosquash --root
    +
         Reencode to utf-8 before arranging rebase's todo list.
     
         Signed-off-by: Doan Tran Cong Danh <congdanhqx@gmail.com>
    -    The todo list shown to user has already been reencoded by sequencer_make_script,
    -    without this patch it looks like this:
    -
    -    $ head -3 .git/rebase-merge/git-rebase-todo | xxd
    -    00000000: 7069 636b 2065 6633 3961 3033 201b 2442  pick ef39a03 .$B
    -    00000010: 244f 1b28 421b 2442 246c 1b28 421b 2442  $O.(B.$B$l.(B.$B
    -    00000020: 2452 1b28 421b 2442 245b 1b28 421b 2442  $R.(B.$B$[.(B.$B
    -    00000030: 2455 1b28 420a 7069 636b 2062 3832 3931  $U.(B.pick b8291
    -    00000040: 3336 2073 7175 6173 6821 201b 2442 244f  36 squash! .$B$O
    -    00000050: 1b28 421b 2442 246c 1b28 421b 2442 2452  .(B.$B$l.(B.$B$R
    -    00000060: 1b28 421b 2442 245b 1b28 421b 2442 2455  .(B.$B$[.(B.$B$U
    -    00000070: 1b28 420a 7069 636b 2062 3532 3132 6437  .(B.pick b5212d7
    -    00000080: 2069 6e74 6572 6d65 6469 6174 6520 636f   intermediate co
    -    00000090: 6d6d 6974 0a                             mmit.
     
      ## sequencer.c ##
     @@ sequencer.c: int todo_list_rearrange_squash(struct todo_list *todo_list)