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Title: gh-142006: Fix HeaderWriteError in email.policy.default caused by extra newline by pareshjoshij · Pull Request #142008 · python/cpython · GitHub

Open Graph Title: gh-142006: Fix HeaderWriteError in email.policy.default caused by extra newline by pareshjoshij · Pull Request #142008 · python/cpython

X Title: gh-142006: Fix HeaderWriteError in email.policy.default caused by extra newline by pareshjoshij · Pull Request #142008 · python/cpython

Description: Description This PR fixes gh-142006 where email.policy.default would raise a HeaderWriteError when folding certain long address headers. The Issue: In _header_value_parser.py, the function _steal_trailing_WSP_if_exists moves trailing whitespace from the previous line to the current one. However, if the previous line contained only that whitespace, it was left as an empty string ''. When joined, this resulted in a double newline (\n\n), which is illegal in headers and triggered the error. The Fix: Modified _steal_trailing_WSP_if_exists to remove the line entirely (lines.pop()) if it becomes empty after stealing the whitespace. Verification: Added a regression test test_fold_address_list_with_stolen_whitespace to Lib/test/test_email/test_policy.py which reproduces the reported crash and verifies the fix. Linked Issue Fixes gh-142006

Open Graph Description: Description This PR fixes gh-142006 where email.policy.default would raise a HeaderWriteError when folding certain long address headers. The Issue: In _header_value_parser.py, the function _steal_t...

X Description: Description This PR fixes gh-142006 where email.policy.default would raise a HeaderWriteError when folding certain long address headers. The Issue: In _header_value_parser.py, the function _steal_t...

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gh-142006: Fix HeaderWriteError in email.policy.default caused by extra newline https://github.com/python/cpython/pull/142008/files#top
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328bbac Fix gh-142006: email.policy.default adds extra newline to headers pareshjoshij Nov 27, 2025 https://github.com/python/cpython/pull/142008/commits/328bbaccc7324ab11d29e615dac5e2a630ed8b8e
45d7830 📜🤖 Added by blurb_it. blurb-it[bot] Nov 27, 2025 https://github.com/python/cpython/pull/142008/commits/45d78301388179fce5f8dc9d419a7ee0601fefd9
8447ed5 Address review: fix comment style and move test pareshjoshij Nov 28, 2025 https://github.com/python/cpython/pull/142008/commits/8447ed57d6d2185a404be8ead82c178c66085b74
7d63071 Merge news file and update text pareshjoshij Nov 28, 2025 https://github.com/python/cpython/pull/142008/commits/7d630710ee9e9da0e156fd0b9f4b4af6ea51533c
55e00ae Fix test logic and comments per review pareshjoshij Dec 6, 2025 https://github.com/python/cpython/pull/142008/commits/55e00ae0d655b751eebbfbff22e18fbebcecc36b
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