patch: make diff --git to differentiate b/w file is empty or doesn't exists...
patch: make diff --git to differentiate b/w file is empty or doesn't exists
Before this patch, as we didn't differentiate the two cases of a file in a context:
1. File doesn't exists
2. File is empty
which causes the blob id to be same for both the cases.
Now we use `nullhex` for a file which doesn't exists in a context (aligning it with
the git diff format)
Changes in test file reflect the fixed behavior.
Differential Revision:
https://phab.mercurial-scm.org/D10001
