editor: file created for diff action should have .diff suffix
This is a follow-up to https://phab.mercurial-scm.org/D464 (
6e6452bc441d) that
introduced the new file extension behavior. It erroneously changed `.diff` to
`.diff.hg.txt`.
Test Plan:
Verified `make tests` passes, particularly `test-editor-filename.t`.
Differential Revision: https://phab.mercurial-scm.org/D607
basic:
* neither file exists
creating
* neither file still exists
* empty file x created
creating
* file x changed size
creating
* nothing changed with either file
* file x changed inode
creating
* empty file y created
creating
* file y changed size
creating
* file y changed inode
creating
* both files changed inode
creating
fakeuncacheable:
* neither file exists
creating
* neither file still exists
creating
* empty file x created
creating
* file x changed size
creating
* nothing changed with either file
creating
* file x changed inode
creating
* empty file y created
creating
* file y changed size
creating
* file y changed inode
creating
* both files changed inode
creating
repository tip rolled back to revision -1 (undo commit)
working directory now based on revision -1
repository tip rolled back to revision -1 (undo commit)
working directory now based on revision -1
setbeforeget:
* neither file exists
string set externally
* file x created
creating
string from function
* string set externally again
string 2 set externally
* file y created
creating
string from function
antiambiguity: