Fix unable to start Medusa due to configparser ImportError (#5145)

* Fix `_configure_syspath` to handle `.pth` files

Fix `configparser`s package structure.
Add missing `.pth` file for configparser
`.pth` file renamed for simplicity - original name: `configparser-3.5.0-py2.7-nspkg.pth`.

* Explain the code better

* Update info on `ext/readme.md`

* Prepare `syspath` code for the future

* Update changelog

CHANGELOG.md

@@ -8,6 +8,8 @@
 - Fixed UI bugs in home page (when using "split home in tabs") and status page ([#5126](https://github.com/pymedusa/Medusa/pull/5126) + [#5127](https://github.com/pymedusa/Medusa/pull/5127))
 - Fixed error due to `null` values in the episodes database table ([#5132](https://github.com/pymedusa/Medusa/pull/5132))
 - Fixed extraneous calls to AniDB when navigating to any show's page ([#5166](https://github.com/pymedusa/Medusa/pull/5166))
+- Fixed being unable to start Medusa due to an import error ([#5145](https://github.com/pymedusa/Medusa/pull/5145))
+
 
 -----
 

ext/configparser.pth

@@ -0,0 +1 @@
+import sys, types, os;has_mfs = sys.version_info > (3, 5);p = os.path.join(sys._getframe(1).f_locals['sitedir'], *('backports',));importlib = has_mfs and __import__('importlib.util');has_mfs and __import__('importlib.machinery');m = has_mfs and sys.modules.setdefault('backports', importlib.util.module_from_spec(importlib.machinery.PathFinder.find_spec('backports', [os.path.dirname(p)])));m = m or sys.modules.setdefault('backports', types.ModuleType('backports'));mp = (m or []) and m.__dict__.setdefault('__path__',[]);(p not in mp) and mp.append(p)

ext/readme.md

@@ -13,7 +13,7 @@
 :: | `chardet` | [3.0.4](https://pypi.org/project/chardet/3.0.4/) | **`medusa`**, `beautifulsoup4`, `feedparser`, `html5lib`, `pysrt`, `requests`, `subliminal` | -
 :: | `cloudflare-scrape` | pymedusa/[320456e](https://github.com/pymedusa/cloudflare-scrape/tree/320456e8b28cedb807363a7a892b1379db843f66) | **`medusa`** | Module: `cfscrape`
 :: | <code><b>configobj</b>.py</code><br>`validate.py`<br>`_version.py` | [5.0.6](https://pypi.org/project/configobj/5.0.6/) | **`medusa`** | -
-:: | <code><b>configparser</b>.py</code><br>`backports.configparser` | [3.5.0](https://pypi.org/project/configparser/3.5.0/) | `adba` | -
+:: | <code><b>configparser</b>.py</code><br>`configparser.pth`<br>`backports.configparser` | [3.5.0](https://pypi.org/project/configparser/3.5.0/) | `adba` | `configparser.pth` was renamed from `configparser-3.5.0-py2.7-nspkg.pth`
 :: | <code><b>contextlib2</b>.py</code> | [0.5.5](https://pypi.org/project/contextlib2/0.5.5/) | **`medusa`**, `tvdbapiv2`, `vcrpy`(?) | Markers: `python_version < '3.5'`
 :: | <code><b>decorator</b>.py</code> | [4.3.0](https://pypi.org/project/decorator/4.3.0/) | `validators` | -
 :: | `dirtyjson` | [1.0.7](https://pypi.org/project/dirtyjson/1.0.7/) | **`medusa`** | -

medusa/init/__init__.py

@@ -8,6 +8,7 @@
 import mimetypes
 import os
 import shutil
+import site
 import sys
 
 
@@ -46,8 +47,39 @@ def _ext_lib_location():
 
 
 def _configure_syspath():
-    sys.path.insert(1, _lib_location())
-    sys.path.insert(1, _ext_lib_location())
+    """Add the vendored libraries into `sys.path`."""
+    # Note: These paths will be inserted into `sys.path` in reverse order (LIFO)
+    # So the last path on this list will be inserted as the first path on `sys.path`
+    # right after the current working dir.
+    # For example: [ cwd, pathN, ..., path1, path0, <rest_of_sys.path> ]
+
+    paths_to_insert = [
+        _lib_location(),
+        _ext_lib_location()
+    ]
+
+    if sys.version_info[0] == 2:
+        # Add Python 2-only vendored libraries
+        paths_to_insert.extend([
+            # path_to_lib2,
+            # path_to_ext2
+        ])
+    elif sys.version_info[0] == 3:
+        # Add Python 3-only vendored libraries
+        paths_to_insert.extend([
+            # path_to_lib3,
+            # path_to_ext3
+        ])
+
+    # Insert paths into `sys.path` and handle `.pth` files
+    # Inspired by: https://bugs.python.org/issue7744
+    for dirpath in paths_to_insert:
+        # Clear `sys.path`
+        sys.path, remainder = sys.path[:1], sys.path[1:]
+        # Add directory as a site-packages directory and handle `.pth` files
+        site.addsitedir(dirpath)
+        # Restore rest of `sys.path`
+        sys.path.extend(remainder)
 
 
 def _register_utf8_codec():