--- a/mercurial/util.py	Tue Apr 13 17:58:38 2010 -0400
+++ b/mercurial/util.py	Wed Apr 14 09:09:43 2010 +0200
@@ -689,7 +689,7 @@
     """check whether the given path is on a symlink-capable filesystem"""
     # mktemp is not racy because symlink creation will fail if the
     # file already exists
-    name = tempfile.mktemp(dir=path)
+    name = tempfile.mktemp(dir=path, prefix='hg-checklink-')
     try:
         os.symlink(".", name)
         os.unlink(name)

--- a/tests/run-tests.py	Tue Apr 13 17:58:38 2010 -0400
+++ b/tests/run-tests.py	Wed Apr 14 09:09:43 2010 +0200
@@ -852,6 +852,11 @@
     os.environ['GREP_OPTIONS'] = ''
     os.environ['http_proxy'] = ''
 
+    # unset env related to hooks
+    for k in os.environ.keys():
+        if k.startswith('HG_'):
+            del os.environ[k]
+
     global TESTDIR, HGTMP, INST, BINDIR, PYTHONDIR, COVERAGE_FILE
     TESTDIR = os.environ["TESTDIR"] = os.getcwd()
     if options.tmpdir: