fix loading gzip compressed cached release with Python 3 (fix #35)

src/rosdistro/__init__.py

@@ -44,7 +44,7 @@
 try:
     from cStringIO import StringIO
 except ImportError:
-    from io import StringIO
+    from io import BytesIO as StringIO
 import yaml
 
 logger = logging.getLogger('rosdistro')
@@ -151,10 +151,12 @@ def get_release_cache(index, dist_name):
     if url.endswith('.yaml'):
         yaml_str = load_url(url)
     elif url.endswith('.yaml.gz'):
-        yaml_gz_str = load_url(url)
+        yaml_gz_str = load_url(url, skip_decode=True)
         yaml_gz_stream = StringIO(yaml_gz_str)
         f = gzip.GzipFile(fileobj=yaml_gz_stream, mode='rb')
         yaml_str = f.read()
+        if not isinstance(yaml_str, str):
+            yaml_str = yaml_str.decode('utf-8')
         f.close()
     else:
         raise NotImplementedError('The url of the cache must end with either ".yaml" or ".yaml.gz"')

src/rosdistro/loader.py

@@ -43,7 +43,7 @@
     from urllib2 import URLError
 
 
-def load_url(url, retry=2, retry_period=1, timeout=10):
+def load_url(url, retry=2, retry_period=1, timeout=10, skip_decode=False):
     try:
         fh = urlopen(url, timeout=timeout)
     except HTTPError as e:
@@ -59,7 +59,7 @@ def load_url(url, retry=2, retry_period=1, timeout=10):
         raise URLError(str(e) + ' (%s)' % url)
     # Python 2/3 Compatibility
     contents = fh.read()
-    if isinstance(contents, str):
+    if isinstance(contents, str) or skip_decode:
         return contents
     else:
         return contents.decode('utf-8')