Issue295 fixes #295 (#296)

* Updated logic to get pandoc releases - issue #295

* Updated appveyor script

* Updated how get get the versions from GitHub, including handling of latest

appveyor.yml

@@ -44,8 +44,8 @@ install:
   - ECHO "Filesystem root:"
   - ps: "ls \"C:/\""
 
-  - ECHO "Installed SDKs:"
-  - ps: "ls \"C:/Program Files/Microsoft SDKs/Windows\""
+  #- ECHO "Installed SDKs:"
+  #- ps: "ls \"C:/Program Files/Microsoft SDKs/Windows\""
 
   # stolen from https://github.com/doxygen/doxygen/blob/master/appveyor.yml
   - appveyor-retry appveyor DownloadFile  https://miktex.org/download/win/miktexsetup-x64.zip

pypandoc/pandoc_download.py

@@ -11,6 +11,7 @@
 import tempfile
 from typing import Union
 
+import urllib
 try:
     from urllib.request import urlopen
 except ImportError:
@@ -45,8 +46,17 @@ def _get_pandoc_urls(version="latest"):
     # url to pandoc download page
     url = "https://github.com/jgm/pandoc/releases/" + \
           ("tag/" if version != "latest" else "") + version
+    # try to open the url
+    try:
+        response = urlopen(url)
+        content = response.read()
+        pattern = re.compile(r"pandoc\s*([\d.]+)")
+        version = re.search(pattern, content.decode("utf-8")).group(1)
+    except urllib.error.HTTPError as e:
+        raise RuntimeError("Invalid pandoc version {}.".format(version))
+        return
     # read the HTML content
-    response = urlopen(url)
+    response = urlopen("https://github.com/jgm/pandoc/releases/expanded_assets/"+version)
     content = response.read()
     # regex for the binaries
     processor_architecture = "arm" if platform.uname()[4].startswith("arm") else "amd"