Detect Debian-related problems and abort.

vdirsyncer/__init__.py

@@ -3,6 +3,7 @@
 vdirsyncer is a synchronization tool for vdir. See the README for more details.
 '''
 
+from __future__ import print_function
 
 try:
     from .version import version as __version__  # noqa
@@ -13,5 +14,31 @@ except ImportError:
         'use the PyPI ones.'
     )
 
+
+def _detect_faulty_requests():
+    import requests
+    if 'dist-packages' not in requests.__file__:
+        return
+
+    text = (
+        '{e}\n\n'
+        'This most likely means you are running into a bug specific to '
+        'Debian-based distributions.\n\n'
+        'Consult {d}/problems.html#requests-related-importerrors-on-debian'
+        '-based-distributions on how to deal with this, or use a different '
+        'operating system.'
+    )
+
+    try:
+        from requests_toolbelt.auth.guess import GuessAuth  # noqa
+    except ImportError as e:
+        import sys
+        print(text.format(e=str(e), d=DOCS_HOME), file=sys.stderr)
+        sys.exit(1)
+
+
+_detect_faulty_requests()
+
+
 PROJECT_HOME = 'https://github.com/untitaker/vdirsyncer'
-DOCS_HOME = 'https://vdirsyncer.readthedocs.org/en/latest'
+DOCS_HOME = 'https://vdirsyncer.readthedocs.org/en/stable'