tests/test-issue1089.t

smtp: verify the certificate of the SMTP server for STARTTLS/SMTPS

Before this patch, the certificate of the SMTP server for STARTTLS or
SMTPS isn't verified.

This may cause man-in-the-middle security problem (stealing
authentication information), even though SMTP channel itself is
encrypted by SSL.

When "[smtp] tls" is configured as "smtps" or "starttls", this patch:

  - uses classes introduced by preceding patches instead of "SMTP" or
    "SMTP_SSL" of smtplib, and

  - verifies the certificate of the SMTP server, if "[smtp]
    verifycert" is configured as other than False

"[smtp] verifycert" can be configured in 3 levels:

  - "strict":

    This verifies peer certificate, and aborts if:

      - peer certification is not valid, or
      - no configuration in "[hostfingerprints]" and "[web] cacerts"

    This is default value of "[smtp] verifycert" for security.

  - "loose":

    This verifies peer certificate, and aborts if peer certification is
    not valid.

    This just shows warning message ("certificate not verified"), if
    there is no configuration in "[hostfingerprints]" and "[web]
    cacerts".

    This is as same as verification for HTTPS connection.

  - False(no verification):

    Peer certificate is not verified.

    This is as same as the behavior before this patch series.

"hg email --insecure" uses "loose" level, and ignores "[web] cacerts"
as same as push/pull/etc... with --insecure.

Ignoring "[web] cacerts" configuration for "hg email --insecure" is
already done in "dispatch._dispatch()" by looking "insecure" up in the
table of command options.

http://mercurial.selenic.com/bts/issue1089

  $ hg init
  $ mkdir a
  $ echo a > a/b
  $ hg ci -Am m
  adding a/b

  $ hg rm a
  removing a/b (glob)
  $ hg ci -m m a

  $ mkdir a b
  $ echo a > a/b
  $ hg ci -Am m
  adding a/b

  $ hg rm a
  removing a/b (glob)
  $ cd b

Relative delete:

  $ hg ci -m m ../a

  $ cd ..