view CONTRIBUTING @ 33494:30f2715be123

sslutil: inform the user about how to fix an incomplete certificate chain

This is a Windows only thing.  Unfortunately, the socket is closed at this point
(so the certificate is unavailable to check the chain).  That means it's printed
out when verification fails as a guess, on the assumption that 1) most of the
time verification won't fail, and 2) sites using expired or certs that are too
new will be rare.  Maybe this is an argument for adding more functionality to
debugssl, to test for problems and print certificate info.  Or maybe it's an
argument for bundling certificates with the Windows builds.  That idea was set
aside when the enhanced SSL code went in last summer, and it looks like there
were issues with using certifi on Windows anyway[1].

This was tested by deleting the certificate out of certmgr.msc > "Third-Party
Root Certification Authorities" > "Certificates", seeing `hg pull` fail (with
the new message), trying this command, and then successfully performing the pull
command.

[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-October/089573.html

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