util: use ~ as a suffix for a temp file in the same directory as a source file
Tools like Buck have patterns to ignore the creation of files (in the working
copy) that match certain patterns:
https://github.com/facebook/buck/blob/
39278a4f0701c5239eae148968dc1ed4cc8661f7/src/com/facebook/buck/cli/Main.java#L259-L299
When Buck sees a new source file (as reported by Watchman), it has to invalidate
a number of caches associated with the directory that contains the file.
Using a standard suffix, such as `~`, would make it easier for Buck and others
to filter out these types of file creation events.
The other uses of `tempfile.mkstemp()` in Hg do not appear to be problematic
because they (generally speaking) do not specify the `dir` parameter, so the
new file is created in the system-appropriate temp directory, which is outside
the working copy.
Test Plan:
`make tests`
Differential Revision: https://phab.mercurial-scm.org/D468
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install::
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing::
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.