bug#25524: 26.0.50; diff-mode is broken

[Dima Kogan]

Noam Postavsky <npostavs@users.sourceforge.net> writes:

> On Wed, Jan 25, 2017 at 11:32 AM, Tino Calancha <tino.calancha@gmail.com> 
> wrote:
>>  ;; "index ", "old mode", "new mode", "new file mode" and
>> -;; "deleted file mode" are output by git-diff.
>> +;; "deleted file mode" are output by git-diff; "Index: " and
>> +;; "========..." by SVN.
>>  (defconst diff-file-junk-re
>> -  "diff \\|index \\|\\(?:deleted file\\|new\\(?: file\\)?\\|old\\) 
>> mode\\|=== modified file")
>> +  (concat "Index: \\|" (make-string 67 ?=) "\\|"
>> +          "diff \\|index \\|\\(?:deleted file\\|new\\(?: file\\)?\\|old\\) 
>> mode\\|=== modified file"))
>
> Is it safe to assume exactly 67 "="? Maybe it would be better to use
> something like "=\\{20,\\}", i.e. a sequence of 20 or more "=".

More broadly, are we sure we need to be touching this? The previous
approach and the one before that worked with the stock regexes.