localrepo: prevent executable-bit only changes from being lost on amend
If you have just executable-bit change and amend it twice it will vanish:
* After the first amend the commit will have the proper executable bit set
in manifest but it won't have the the file on the list of files in
changelog.
* The second amend will read the wrong list of files from changelog and it
will copy the manifest entry from parent for this file.
* Voila! The change is lost.
This change repairs the bug in localrepo causing this and adds a test for it.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true