avoid using broken os.path.commonprefix

.gitignore

@@ -10,6 +10,7 @@ docs/_build/
 *.egg-info
 .coverage
 coverage/
+tests/static/
 tests/assets/js/dummy.js
 .tox/
 .DS_Store
\ No newline at end of file

pipeline/compressors/__init__.py

@@ -3,6 +3,8 @@ import os
 import re
 import subprocess
 
+from itertools import takewhile
+
 from pipeline.conf import settings
 from pipeline.storage import storage
 from pipeline.utils import to_class, relpath
@@ -80,7 +82,7 @@ class Compressor(object):
         if not paths:
             return compiled
         namespace = settings.PIPELINE_TEMPLATE_NAMESPACE
-        base_path = os.path.commonprefix(paths)
+        base_path = self.base_path(paths)
         for path in paths:
             contents = self.read_file(path)
             contents = re.sub(r"\r?\n", "", contents)
@@ -97,6 +99,12 @@ class Compressor(object):
             compiled
         ])
 
+    def base_path(self, paths):
+        def names_equal(name):
+            return all(n==name[0] for n in name[1:])
+        directory_levels = zip(*[p.split(os.sep) for p in paths])
+        return os.sep.join(x[0] for x in takewhile(names_equal, directory_levels))
+
     def template_name(self, path, base):
         """Find out the name of a JS template"""
         if not base:

tests/tests/compressor.py

@@ -50,6 +50,12 @@ class CompressorTest(TestCase):
         relative_path = self.compressor.relative_path('/var/www/static/images/sprite.png')
         self.assertEquals(relative_path, '/images/sprite.png')
 
+    def test_base_path(self):
+        base_path = self.compressor.base_path([
+            'js/templates/form.jst', 'js/templates/field.jst'
+        ])
+        self.assertEquals(base_path, 'js/templates')
+
     def test_absolute_path(self):
         absolute_path = self.compressor.absolute_path('../../images/sprite.png',
             'css/plugins/')