Merge branch 'nd/ita-empty-commit'
When new paths were added by "git add -N" to the index, it was
enough to circumvent the check by "git commit" to refrain from
making an empty commit without "--allow-empty". The same logic
prevented "git status" to show such a path as "new file" in the
"Changes not staged for commit" section.
* nd/ita-empty-commit:
commit: don't be fooled by ita entries when creating initial commit
commit: fix empty commit creation when there's no changes but ita entries
diff: add --ita-[in]visible-in-index
diff-lib: allow ita entries treated as "not yet exist in index"