tests/test-rebase-newancestor.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.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > graphlog=
  > rebase=
  > 
  > [alias]
  > tglog = log -G --template "{rev}: '{desc}' {branches}\n"
  > EOF

  $ hg init repo
  $ cd repo

  $ echo A > a
  $ echo >> a
  $ hg ci -Am A
  adding a

  $ echo B > a
  $ echo >> a
  $ hg ci -m B

  $ echo C > a
  $ echo >> a
  $ hg ci -m C

  $ hg up -q -C 0

  $ echo D >> a
  $ hg ci -Am AD
  created new head

  $ hg tglog
  @  3: 'AD'
  |
  | o  2: 'C'
  | |
  | o  1: 'B'
  |/
  o  0: 'A'
  
  $ hg rebase -s 1 -d 3
  merging a
  merging a
  saved backup bundle to $TESTTMP/repo/.hg/strip-backup/*-backup.hg (glob)

  $ hg tglog
  @  3: 'C'
  |
  o  2: 'B'
  |
  o  1: 'AD'
  |
  o  0: 'A'
  

  $ cd ..