templater: simplify templatepaths() to avoid iterating a singleton list

The function iterates over a hard-coded list of one element since
d844e220792a (templater: don't search randomly for templates - trust
util.datapath, 2014-09-28).

Differential Revision: https://phab.mercurial-scm.org/D8785

mercurial/templater.py

@@ -1047,12 +1047,8 b' class templater(object):'
 
 def templatepaths():
     '''return locations used for template files.'''
-    pathsrel = [b'templates']
-    paths = [
-        os.path.normpath(os.path.join(resourceutil.datapath, f))
-        for f in pathsrel
-    ]
-    return [p for p in paths if os.path.isdir(p)]
+    path = os.path.normpath(os.path.join(resourceutil.datapath, b'templates'))
+    return [path] if os.path.isdir(path) else []
 
 
 def templatepath(name):