[PATCH v2 0/2] diff: index-line: respect --abbrev in object's name

For diff-family, Git supports 2 different options for 2 different purposes, `--full-index' for showing diff-patch object's name in full, and `--abbrev' to customize the length of object names in diff-raw and diff-tree header lines, without any options to customise the length of object names in diff-patch format. When working with diff-patch format, we only have two options, either full index, or default abbrev length.

Although, that consistent is documented, it doesn't stop users from trying to use `--abbrev' with the hope of customising diff-patch's objects' name's abbreviation.

Let's resolve that inconsistency.

Đoàn Trần Công Danh (2):
  revision: differentiate if --no-abbrev asked explicitly
  diff: index-line: respect --abbrev in object's name

 Documentation/diff-options.txt                |  9 +++---
 diff.c                                        |  5 +++-
 revision.c                                    |  2 +-
 t/t4013-diff-various.sh                       |  3 ++
 ...ff.diff-tree_--root_-p_--abbrev=10_initial | 29 +++++++++++++++++++
 ...--root_-p_--full-index_--abbrev=10_initial | 29 +++++++++++++++++++
 ...f.diff-tree_--root_-p_--full-index_initial | 29 +++++++++++++++++++
 7 files changed, 100 insertions(+), 6 deletions(-)
 create mode 100644 t/t4013/diff.diff-tree_--root_-p_--abbrev=10_initial
 create mode 100644 t/t4013/diff.diff-tree_--root_-p_--full-index_--abbrev=10_initial
 create mode 100644 t/t4013/diff.diff-tree_--root_-p_--full-index_initial

Range-diff against v1:
1:  9daef7445c = 1:  9daef7445c revision: differentiate if --no-abbrev asked explicitly
2:  9146313893 ! 2:  12acf1fe5d diff: extend --abbrev support to diff-patch format
    @@ Metadata
     Author: Đoàn Trần Công Danh <congdanhqx@gmail.com>
     
      ## Commit message ##
    -    diff: extend --abbrev support to diff-patch format
    +    diff: index-line: respect --abbrev in object's name
    +
    +    A handful of Git's commands respect `--abbrev' for customizing length
    +    of abbreviation of object names.
    +
    +    For diff-family, Git supports 2 different options for 2 different
    +    purposes, `--full-index' for showing diff-patch object's name in full,
    +    and `--abbrev' to customize the length of object names in diff-raw and
    +    diff-tree header lines, without any options to customise the length of
    +    object names in diff-patch format. When working with diff-patch format,
    +    we only have two options, either full index, or default abbrev length.
    +
    +    Although, that consistent is documented, it doesn't stop users from
    +    trying to use `--abbrev' with the hope of customising diff-patch's
    +    objects' name's abbreviation.
    +
    +    Let's resolve that inconsistency.
    +
    +    To preserve backward compatibility with old script that specify both
    +    `--full-index' and `--abbrev', always shows full object id
    +    if `--full-index' is specified.
     
         Signed-off-by: Đoàn Trần Công Danh <congdanhqx@gmail.com>