Fix extremely incorrect PEM parsing #2567

Job	Run time
Test	1m 3s
build_versions (stable)	2m 49s
Test (charset)	44s
Test	30s
build_versions (beta)	3m 0s
Test (cookies)	46s
Test (charset)	33s
build_versions (1.71.1)	3m 1s
Test (socks-proxy)	50s
Test (cookies)	42s
Test (gzip)	1m 0s
Test (socks-proxy)	44s
Test (brotli)	42s
Test (gzip)	33s
cargo-deny (aarch64-apple-ios)	21s
Test (brotli)	30s
Test (json)	57s
Docs	1m 25s
cargo-deny (aarch64-linux-android)	19s
Test (json)	40s
Test (native-tls)	49s
Test (native-tls)	40s
cargo-deny (i686-pc-windows-gnu)	19s
cargo-deny (i686-pc-windows-msvc)	20s
Lint	19s
cargo-deny (i686-unknown-linux-gnu)	17s
cargo-deny (wasm32-unknown-unknown)	20s
cargo-deny (x86_64-apple-darwin)	20s
cargo-deny (x86_64-apple-ios)	18s
cargo-deny (x86_64-pc-windows-gnu)	20s
cargo-deny (x86_64-pc-windows-msvc)	25s
cargo-deny (x86_64-unknown-linux-gnu)	18s
cargo-deny (x86_64-unknown-redox)	20s
	26m 14s

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