Re: [PATCH] Make !pattern in .gitattributes non-fatal

Thomas Rast [off-list ref] writes:

Before 82dce99 (attr: more matching optimizations from .gitignore,
2012-10-15), .gitattributes did not have any special treatment of a
leading '!'.  The docs, however, always said

  The rules how the pattern matches paths are the same as in
  `.gitignore` files; see linkgit:gitignore[5].

By those rules, leading '!' means pattern negation.  So 82dce99
correctly determined that this kind of line makes no sense and should
be disallowed.

However, users who actually had a rule for files starting with a '!'
are in a bad position: before 82dce99 '!' matched that literal
character, so it is conceivable that users have .gitattributes with
such lines in them.  After 82dce99 the unescaped version was
disallowed in such a way that git outright refuses to run(!) most
commands in the presence of such a .gitattributes.  It therefore
becomes very hard to fix, let alone work with, such repositories.

Fixing the working tree is easy, but when we read from a history
that already records such an entry in an attribute file, it would
become somewhat cumbersome.  I wouldn't use "very hard to fix" to
describe such a case.

But the demotion to warning does make sense; let's do that in
v1.8.1.5.