Re: [PATCHv4] pathspec: allow escaped query values

> In our own .gitattributes file we have attributes such as:
>
>     *.[ch] whitespace=indent,trail,space
>
> When querying for attributes we want to be able to ask for the exact
> value, i.e.
>
>     git ls-files :(attr:whitespace=indent,trail,space)
>
> should work, but the commas are used in the attr magic to introduce
> the next attr, such that this query currently fails with
>
> fatal: Invalid pathspec magic 'trail' in ':(attr:whitespace=indent,trail,space)'
>
> This change allows escaping characters by a backslash, such that the query
>
>     git ls-files :(attr:whitespace=indent\,trail\,space)
>
> will match all path that have the value "indent,trail,space" for the
> whitespace attribute. To accomplish this, we need to modify two places.
> First `eat_long_magic` needs to not stop early upon seeing a comma or
> closing paren that is escaped. As a second step we need to remove any
> escaping from the attr value.
>
> Helped-by: Junio C Hamano <gitster@pobox.com>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
>
> differences to v3 (http://thread.gmane.org/gmane.comp.version-control.git/296259):
> * lose the *src check before invalid_value_char
> * remove a stray new line in parse_pathspec_attr_match
>
> Thanks,
> Stefan