bugfix in pactest when creating a symlink at the top level.

Trying to make a symlink at the top level previously made pactest fail.
For example : "test -> test2/" as a file in a package.

The path to the test symlink was empty in this case, but the python code
still tried to chdir in "", which failed.

Signed-off-by: Chantry Xavier <shiningxc@gmail.com>

pactest/util.py

@@ -103,6 +103,7 @@ def mkfile(name, data = ""):
         return
     if islink:
         curdir = os.getcwd()
+        if path:
             os.chdir(path)
         os.symlink(link, os.path.basename(filename))
         os.chdir(curdir)