Sync with 1.8.1 maintenance track

* maint-1.8.1:
Start preparing for 1.8.1.6
git-tag(1): we tag HEAD by default
Fix revision walk for commits with the same dates
t2003: work around path mangling issue on Windows
pack-refs: add fully-peeled trait
pack-refs: write peeled entry for non-tags
use parse_object_or_die instead of die("bad object")
avoid segfaults on parse_object failure
entry: fix filter lookup
t2003: modernize style
name-hash.c: fix endless loop with core.ignorecase=true

diff --cc Documentation/git-tag.txt
Simple merge

diff --cc builtin/grep.c
index 8025964987553b8f1ef21b8319b2085d6d31bb0c,e8f0f92cf739c87c19d2be1722b6093ddbed7330..159e65d47a41b56634bc3fb480f9c051d40e692c
--- 1/builtin/grep.c
--- 2/builtin/grep.c
+++ b/builtin/grep.c
@@@ -820,11 -820,7 +820,9 @@@ int cmd_grep(int argc, const char **arg
                unsigned char sha1[20];
                /* Is it a rev? */
                if (!get_sha1(arg, sha1)) {
-                       struct object *object = parse_object(sha1);
-                       if (!object)
-                               die(_("bad object %s"), arg);
+                       struct object *object = parse_object_or_die(sha1, arg);
 +                      if (!seen_dashdash)
 +                              verify_non_filename(prefix, arg);
                        add_object_array(object, arg, &list);
                        continue;
                }

diff --cc cache.h
Simple merge

diff --cc name-hash.c
Simple merge

diff --cc read-cache.c
Simple merge

diff --cc refs.c
Simple merge

diff --cc revision.c
Simple merge