[PATCH 2 of 4] hghave: add test for whether fsmonitor is enabled

[Siddharth Agarwal]

# HG changeset patch
# User Siddharth Agarwal <sid0 at fb.com>
# Date 1497128851 25200
#      Sat Jun 10 14:07:31 2017 -0700
# Node ID a69ae05fa66239c2aecb3673115de82105c8e9c6
# Parent  af12ded5040ae8b5becf5c354aafe19949d93444
hghave: add test for whether fsmonitor is enabled

This uses the HGFSMONITOR_TESTS environment variable that
fsmonitor-run-tests.py adds.

diff --git a/tests/hghave.py b/tests/hghave.py
--- a/tests/hghave.py
+++ b/tests/hghave.py
@@ -643,3 +643,7 @@ def has_virtualenv():
         return True
     except ImportError:
         return False
+
+ at check("fsmonitor", "running tests with fsmonitor")
+def has_fsmonitor():
+    return 'HGFSMONITOR_TESTS' in os.environ