diff -r c9c10430fd7f -r 576474baa209 mercurial/win32.py
--- a/mercurial/win32.py	Tue Dec 11 22:23:39 2018 +0900
+++ b/mercurial/win32.py	Tue Dec 11 21:57:54 2018 -0500
@@ -588,6 +588,9 @@
     if not res:
         raise ctypes.WinError()
 
+    _kernel32.CloseHandle(pi.hProcess)
+    _kernel32.CloseHandle(pi.hThread)
+
     return pi.dwProcessId
 
 def unlink(f):