[PATCH 1 of 3] hghave: enable 'serve' on Windows

[Matt Harbison]

# HG changeset patch
# User Matt Harbison <matt_harbison at yahoo.com>
# Date 1494183520 14400
#      Sun May 07 14:58:40 2017 -0400
# Node ID 6b3ae1f8640922b49467a52f197bc1014b3f34ff
# Parent  29558247b00eff8c95c7604032b59cfbab34010d
hghave: enable 'serve' on Windows

I've been using a local hghaveaddon.py to enable this for a couple of months
with reasonable success, and 'killdaemons' is already enabled on Windows.
There's one failure[1] in test-http-proxy.t that this adds, which I can't figure
out.

[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-April/096987.html

diff --git a/tests/hghave.py b/tests/hghave.py
--- a/tests/hghave.py
+++ b/tests/hghave.py
@@ -502,7 +502,7 @@
 
 @check("serve", "platform and python can manage 'hg serve -d'")
 def has_serve():
-    return os.name != 'nt' # gross approximation
+    return True
 
 @check("test-repo", "running tests from repository")
 def has_test_repo():