patch: correctly handle non-tabular Subject: line The line content of continued Subject: lines was yet joined via str.replace('\n\t', ' '), which does not handle continuation via spaces. So expan the regular expression instead to handle all allowed forms of mail header line continuation.

util: fix crash converting an invalid future date to string Post-2038 timestamps cannot be handled on 32-bit architectures. Clamp such dates to the maximum 32-bit timestamp.