[PATCH] index-format.txt: be more liberal on what can represent invalid cache tree

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

We have been writing -1 as "invalid" since day 1. On that same day we
accept all negative entry counts as "invalid". So in theory all C Git
versions out there would be happy to accept any negative numbers. JGit
seems to do exactly the same.

Correct the document to reflect the fact that -1 is not the only magic
number. At least one implementation, libgit2, is found to treat -1
this way.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/technical/index-format.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt
index 9d25b30..2028a49 100644
--- a/Documentation/technical/index-format.txt
+++ b/Documentation/technical/index-format.txt
@@ -161,8 +161,8 @@ GIT index format
     this span of index as a tree.
 
   An entry can be in an invalidated state and is represented by having
-  -1 in the entry_count field. In this case, there is no object name
-  and the next entry starts immediately after the newline.
+  a negative number in the entry_count field. In this case, there is no
+  object name and the next entry starts immediately after the newline.
 
   The entries are written out in the top-down, depth-first order.  The
   first entry represents the root level of the repository, followed by the
-- 
1.8.0.rc2.23.g1fb49df