sslutil: abort when ssl module is needed but not found It is apparently possible to compile Python without SSL support or leave it out when installing precompiled binaries. Mercurial on such Pythons would crash if the user tried to use https. Now it will be reported as "abort: Python SSL support not found" instead.

merge with stable

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.