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

--- a/mercurial/util.py	Mon Aug 28 14:47:18 2017 -0700
+++ b/mercurial/util.py	Tue Aug 22 00:38:38 2017 +0000
@@ -1525,7 +1525,7 @@
     Returns the name of the temporary file.
     """
     d, fn = os.path.split(name)
-    fd, temp = tempfile.mkstemp(prefix='.%s-' % fn, dir=d)
+    fd, temp = tempfile.mkstemp(prefix='.%s-' % fn, suffix='~', dir=d)
     os.close(fd)
     # Temporary files are created with mode 0600, which is usually not
     # what we want.  If the original file already exists, just copy