Re: diff weirdness (bug?)

[Junio C Hamano <gitster@pobox.com>]

Dario Bertini <berdario@gmail.com> writes:

> git clone git@github.com:ansible/ansible.git
> git revert 3616dffb68badb2b8d56
>
> manually solve the conflict (you can look at the commit here:
> https://github.com/ansible/ansible/commit/3616dffb68badb2b8d56ef34391d7aae8de79cd6
> )
>
> git diff will output:
>
> dario@macbook ~/P/ansible (devel*+|REVERTING)> git diff
> diff --cc lib/ansible/constants.py
> index c055ccf,6eac602..0000000
> --- a/lib/ansible/constants.py
> +++ b/lib/ansible/constants.py
> @@@ -84,16 -61,8 +84,12 @@@ active_user   = pwd.getpwuid(os.geteuid
>
>   # Needed so the RPM can call setup.py and have modules land in the
>   # correct location. See #1277 for discussion
> - if getattr(sys, "real_prefix", None):
> -     # in a virtualenv
> -     DIST_MODULE_PATH = os.path.join(sys.prefix, 'share/ansible/')
> - else:
> -     DIST_MODULE_PATH = '/usr/share/ansible/'
> + DIST_MODULE_PATH = os.path.join(sys.prefix, 'share/ansible/')
>
>  +# check all of these extensions when looking for yaml files for things
> like
>  +# group variables
>  +YAML_FILENAME_EXTENSIONS = [ "", ".yml", ".yaml" ]
>  +
>   # sections in config file
>   DEFAULTS='defaults'
>
>
>
> now, it weirdly/incorrectly says that we added the YAML-related lines

This is a combined diff, and yaml-related lines are added relative
to your _other_ branch you are merging (notice these + are indented
by one place).  Relative to what you had at the tip of your branch
before you started this operation that ended up conflicted, the
half-merged result removes if/else that sets DIST_MODULE_PATH and
replaces it with a single line (their +/- are on the first column,
signifying that these are differences relative to the first parent,
i.e. your state before you started the operation).

> if we remove these 3 lines, we'll get this diff:

With that understanding, I think the output after removing these
three lines is perfectlyh understandable and correct.  You are
looking at the three lines that used to exist in the version you
started from, that were missing from the other side.  If you remoe
them, it will show as removal from _your_ version (notice these -
that shows what _you_ did manually are on the first column, saying
that that is relative to _your_ version).