[patreon] fix pagination (#444)

The Patreon-provided URLs for the next set of posts aren't
always complete, i.e. they can be missing their scheme and
the subsequent double slash: "www.patreon.com/…"

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Changelog
 
+## Unreleased
+
 ## 1.10.6 - 2019-10-11
 ### Additions
 - `--exec` command-line option to specify a command to run after each file download ([#421](https://github.com/mikf/gallery-dl/issues/421))

gallery_dl/extractor/patreon.py

@@ -76,6 +76,8 @@ def _pagination(self, url):
         headers = {"Referer": self.root}
 
         while url:
+            if not url.startswith("http"):
+                url = "https://" + url.lstrip("/:")
             posts = self.request(url, headers=headers).json()
 
             if "included" in posts:

gallery_dl/version.py

@@ -6,4 +6,4 @@
 # it under the terms of the GNU General Public License version 2 as
 # published by the Free Software Foundation.
 
-__version__ = "1.10.6"
+__version__ = "1.10.7-dev"