diff weirdness (bug?)

> 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).
> 

> On 02/14/2014 09:03 PM, Junio C Hamano wrote:
>> 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).
>> 
>
> Thank you, I was completely unaware of combined diffs. Still: I can't
> see how this would explain the empty diff when deleting 4 lines instead
> of 3.

> On 02/14/2014 09:03 PM, Junio C Hamano wrote:
>> 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).
>> 
>
> Thank you, I was completely unaware of combined diffs. Still: I can't
> see how this would explain the empty diff when deleting 4 lines instead
> of 3.
>
> Also: in the diff output I get 2 hashes, but these are not the hashes of
> the commits, but the contents of the files apparently. One should be
> HEAD (but if I run sha1sum over the file the hash doesn't match), but

> the other can't be the commit which I reverted: the diff is too small...
> or at least this is what I understand
>
> By the way, in the man of git diff there's the briefly mentioned '-m'
> flag. If anyone else reading this mail in the archives is confused by
> the combined diff output, just use "git diff -m HEAD"... I'll probably
> add this in my git aliases