fixup! Switch LGPL'd chardet for MIT licensed charset_normalizer

HISTORY.md

@@ -8,8 +8,9 @@ dev
 
 **Dependencies**
 
-- Switch chardet for the MIT-licensed charset_normalizer to remove license
-  ambiguity for projects bundling requests.
+- Switch chardet for the MIT-licensed charset_normalizer for Python3 to remove license
+  ambiguity for projects bundling requests. Python2 still depends upon the
+  LGPL'd module.
 
 2.25.1 (2020-12-16)
 -------------------

requests/__init__.py

@@ -41,12 +41,20 @@
 """
 
 import urllib3
-import charset_normalizer
 import warnings
 from .exceptions import RequestsDependencyWarning
 
+try:
+    from charset_normalizer import __version__ as charset_normalizer_version
+except ImportError:
+    charset_normalizer_version = None
+
+try:
+    from chardet import __version__ as chardet_version
+except ImportError:
+    chardet_version = None
 
-def check_compatibility(urllib3_version, charset_normalizer_version):
+def check_compatibility(urllib3_version, chardet_version, charset_normalizer_version):
     urllib3_version = urllib3_version.split('.')
     assert urllib3_version != ['dev']  # Verify urllib3 isn't installed from git.
 
@@ -63,10 +71,16 @@ def check_compatibility(urllib3_version, charset_normalizer_version):
     assert minor <= 26
 
     # Check charset_normalizer for compatibility.
-    major, minor, patch = charset_normalizer_version.split('.')[:3]
-    major, minor, patch = int(major), int(minor), int(patch)
-    # charset_normalizer >= 3.0.2, < 5.0.0
-    assert (1, 3, 5) <= (major, minor, patch) < (2, 0, 0)
+    if chardet_version:
+        major, minor, patch = chardet_version.split('.')[:3]
+        major, minor, patch = int(major), int(minor), int(patch)
+        # chardet_version >= 3.0.2, < 5.0.0
+        assert (3, 0, 2) <= (major, minor, patch) < (5, 0, 0)
+    else:
+        major, minor, patch = charset_normalizer_version.split('.')[:3]
+        major, minor, patch = int(major), int(minor), int(patch)
+        # charset_normalizer >= 1.3.5, < 2.0.0
+        assert (1, 3, 5) <= (major, minor, patch) < (2, 0, 0)
 
 
 def _check_cryptography(cryptography_version):
@@ -82,10 +96,10 @@ def _check_cryptography(cryptography_version):
 
 # Check imported dependencies for compatibility.
 try:
-    check_compatibility(urllib3.__version__, charset_normalizer.__version__)
+    check_compatibility(urllib3.__version__, chardet_version, charset_normalizer_version)
 except (AssertionError, ValueError):
-    warnings.warn("urllib3 ({}) or charset_normalizer ({}) doesn't match a supported "
-                  "version!".format(urllib3.__version__, charset_normalizer.__version__),
+    warnings.warn("urllib3 ({}) or chardet ({})/charset_normalizer ({}) doesn't match a supported "
+                  "version!".format(urllib3.__version__, chardet_version, charset_normalizer_version),
                   RequestsDependencyWarning)
 
 # Attempt to enable urllib3's fallback for SNI support

setup.py

@@ -41,7 +41,8 @@ def run_tests(self):
 packages = ['requests']
 
 requires = [
-    'charset_normalizer>=1.3.5,<2',
+    'charset_normalizer>=1.3.5,<2; python_version >= "3"',
+    'chardet>=3.0.2,<5; python_version < "3"',
     'idna>=2.5,<3',
     'urllib3>=1.21.1,<1.27',
     'certifi>=2017.4.17'