<p dir="auto"></p><div class="Box Box--condensed my-2">
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      <a href="https://github.com/psf/requests/blob/143150233162d609330941ec2aacde5ed4caa510/requests/utils.py#L497">requests/requests/utils.py</a>
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    <p class="mb-0 color-fg-muted">
         Line 497
      in
      <a data-pjax="true" class="commit-tease-sha" href="/psf/requests/commit/143150233162d609330941ec2aacde5ed4caa510">1431502</a>
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  <div itemprop="text" class="Box-body p-0 blob-wrapper blob-wrapper-embedded data">
    <table class="highlight tab-size mb-0 js-file-line-container" data-tab-size="8" data-paste-markdown-skip="">

        <tbody><tr class="border-0">
          <td id="L497" class="blob-num border-0 px-3 py-0 color-bg-default" data-line-number="497"></td>
          <td id="LC497" class="blob-code border-0 px-3 py-0 color-bg-default blob-code-inner js-file-line"> <span class="pl-k">if</span> <span class="pl-s">'text'</span> <span class="pl-c1">in</span> <span class="pl-s1">content_type</span>: </td>
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<br>
From <a href="https://tools.ietf.org/html/rfc2616#section-3.7.1" rel="nofollow">RFC 2616</a>:<br>
When no explicit charset parameter is provided by the sender, media subtypes of the "text"<br>
type are defined to have a default charset value of "ISO-8859-1" when received via HTTP.<p></p>
<p dir="auto">However, from <a href="https://tools.ietf.org/html/rfc7231#appendix-B" rel="nofollow">RFC7231</a>:<br>
The default charset of ISO-8859-1 for text media types has been removed;</p>
<p dir="auto">Actually, if requests uses the default charset of ISO-8859-1, the property text of response will  always lose the efficiency of chardet and cause messy code problem.<br>
I think these lines should be deleted.</p>
<p dir="auto">Referring to these lines: <a href="https://github.com/kennethreitz/requests/blob/master/requests/sessions.py#L457-L458">https://github.com/kennethreitz/requests/blob/master/requests/sessions.py#L457-L458</a></p>
<p dir="auto"><strong>attrs</strong> is not defined and hence pickling of the session fails.</p>