Better fix for #307 is to return text stream from Popen

`universal_newlines` make this in compatible way with older Python.

lib/fetch.py

@@ -57,13 +57,15 @@ def fetch_all(skip_existing=True):
             sys.stdout.write("Fetching %s..." % (adptr))
             sys.stdout.flush()
             try:
-                process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+                process = subprocess.Popen(
+                        cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
+                        universal_newlines=True)
             except OSError:
                 print("\nERROR: %s" % cmd)
                 raise
             output = process.communicate()[0]
             if process.returncode != 0:
-                sys.stdout.write("\nERROR:\n---\n" + str(output))
+                sys.stdout.write("\nERROR:\n---\n" + output)
                 fatal("---\nCould not fetch %s" % adptr)
             else:
                 print("Done")