setup: don't skip the search for global hg.exe if there is no local instance The point of trying not to blindly execute `hg` on Windows is that the local hg.exe would be given precedence, and if py3 isn't on PATH, it errors out with a modal dialog. But that's not a problem if there is no local executable that could be run. The problem that I recently ran into was I upgraded the repo format to use zstd. But doing a `make clean` deletes all of the supporting libraries, causing the next run to abort with a message about not understanding the `revlog-compression-zstd` requirement. By getting rid of the local executable in the previous commit when cleaning, we avoid leaving a broken executable around, and avoid the py3 PATH problem too. There is still a small hole in that `hg.exe` needs to be deleted before switching between py2/py3/PyOxidizer builds, because the zstd module won't load. But that seems like good hygiene anyway. Differential Revision: https://phab.mercurial-scm.org/D8038

--- a/setup.py	Tue Jan 28 22:35:08 2020 -0500
+++ b/setup.py	Tue Jan 28 22:27:30 2020 -0500
@@ -323,7 +323,7 @@
     # gives precedence to hg.exe in the current directory, so fall back to the
     # python invocation of local hg, where pythonXY.dll can always be found.
     check_cmd = ['log', '-r.', '-Ttest']
-    if os.name != 'nt':
+    if os.name != 'nt' or not os.path.exists("hg.exe"):
         try:
             retcode, out, err = runcmd(hgcmd + check_cmd, hgenv)
         except EnvironmentError: