Bump urllib3 from 1.26.7 to 1.26.8 (#1607)

* Bump urllib3 from 1.26.7 to 1.26.8

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.7 to 1.26.8.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/1.26.8/CHANGES.rst)
- [Commits](https://github.com/urllib3/urllib3/compare/1.26.7...1.26.8)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

* Update urllib3==1.26.8

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: JonnyWong16 <9099342+JonnyWong16@users.noreply.github.com>

[skip ci]

lib/urllib3/connectionpool.py

@@ -2,6 +2,7 @@ from __future__ import absolute_import
 
 import errno
 import logging
+import re
 import socket
 import sys
 import warnings
@@ -35,7 +36,6 @@ from .exceptions import (
 )
 from .packages import six
 from .packages.six.moves import queue
-from .packages.ssl_match_hostname import CertificateError
 from .request import RequestMethods
 from .response import HTTPResponse
 from .util.connection import is_connection_dropped
@@ -44,6 +44,7 @@ from .util.queue import LifoQueue
 from .util.request import set_file_position
 from .util.response import assert_header_parsing
 from .util.retry import Retry
+from .util.ssl_match_hostname import CertificateError
 from .util.timeout import Timeout
 from .util.url import Url, _encode_target
 from .util.url import _normalize_host as normalize_host
@@ -301,8 +302,11 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
             pass
         except queue.Full:
             # This should never happen if self.block == True
-            log.warning("Connection pool is full, discarding connection: %s", self.host)
-
+            log.warning(
+                "Connection pool is full, discarding connection: %s. Connection pool size: %s",
+                self.host,
+                self.pool.qsize(),
+            )
         # Connection never got put back into the pool, close it.
         if conn:
             conn.close()
@@ -745,7 +749,33 @@ class HTTPConnectionPool(ConnectionPool, RequestMethods):
             # Discard the connection for these exceptions. It will be
             # replaced during the next _get_conn() call.
             clean_exit = False
-            if isinstance(e, (BaseSSLError, CertificateError)):
+
+            def _is_ssl_error_message_from_http_proxy(ssl_error):
+                # We're trying to detect the message 'WRONG_VERSION_NUMBER' but
+                # SSLErrors are kinda all over the place when it comes to the message,
+                # so we try to cover our bases here!
+                message = " ".join(re.split("[^a-z]", str(ssl_error).lower()))
+                return (
+                    "wrong version number" in message or "unknown protocol" in message
+                )
+
+            # Try to detect a common user error with proxies which is to
+            # set an HTTP proxy to be HTTPS when it should be 'http://'
+            # (ie {'http': 'http://proxy', 'https': 'https://proxy'})
+            # Instead we add a nice error message and point to a URL.
+            if (
+                isinstance(e, BaseSSLError)
+                and self.proxy
+                and _is_ssl_error_message_from_http_proxy(e)
+            ):
+                e = ProxyError(
+                    "Your proxy appears to only use HTTP and not HTTPS, "
+                    "try changing your proxy URL to be HTTP. See: "
+                    "https://urllib3.readthedocs.io/en/1.26.x/advanced-usage.html"
+                    "#https-proxy-error-http-proxy",
+                    SSLError(e),
+                )
+            elif isinstance(e, (BaseSSLError, CertificateError)):
                 e = SSLError(e)
             elif isinstance(e, (SocketError, NewConnectionError)) and self.proxy:
                 e = ProxyError("Cannot connect to proxy.", e)