Currently, bootstrapBuildout is called unconditionally, and since
Software Releases use slapos.reboostrap, we end up with the
following behaviour in the best case:

    Processing software releases...
    Installing software release /srv/slapgrid/slappart9/srv/testnode/aai/software.cfg...
    Generated script '/srv/slapgrid/slappart9/srv/testnode/aai/soft/08f8010370c519147fe23fed3170be9e/bin/buildout'.
    slapos.rebootstrap: Make sure that the section 'python2.7' won't be reinstalled after rebootstrap.
    Unused options for buildout: 'allowed-eggs-from-site-packages' 'exec-sitecustomize' 'include-site-packages' 'unzip'.
    Updating xz-utils.
    Updating patch.
    ...
    Updating gcc.
    Updating python2.7.
    Stripping binaries ...
    Done.
    slapos.rebootstrap:
    ************ REBOOTSTRAP: IMPORTANT NOTICE ************
    bin/buildout is being reinstalled right now, as new python:
      /srv/slapgrid/slappart9/srv/testnode/aai/soft/08f8010370c519147fe23fed3170be9e/parts/python2.7/bin/python2.7
    is available, and buildout is using another python:
      /opt/slapgrid/b9f9e0967ab8491759399f306d65239a/parts/python2.7/bin/python2.7
    Buildout will be restarted automatically to have this change applied.
    ************ REBOOTSTRAP: IMPORTANT NOTICE ************

    Unused options for buildout: 'allowed-eggs-from-site-packages' 'exec-sitecustomize' 'include-site-packages' 'unzip'.
    Updating xz-utils.
    Updating patch.
    ...
    Updating gcc.
    Updating python2.7.
    Updating autoconf.
    ...

Which means that bin/buildout always runs twice: updating parts is usually fast
but loading extends and checking that binaries are stripped can take a while.

The idea of this commit is minimize the amount of work when bin/buildout
already exists, in particular if it is already changed by slapos.reboostrap
to use the built Python. We also hope this will avoid complete rebuilds when
building a different version of Python:

    Installing software release /srv/slapgrid/slappart1/srv/testnode/bsu/software.cfg...
    Generated script '/srv/slapgrid/slappart1/srv/testnode/bsu/soft/90adf14823b5e2bc7dd89ccfbd9388df/bin/buildout'.
    slapos.rebootstrap: Make sure that the section 'python3.5' won't be reinstalled after rebootstrap.
    Uninstalling python3.5.
    Uninstalling file.
    Uninstalling file-msooxml.
    Uninstalling gettext.
    Uninstalling lunzip.
    Uninstalling libxml2.
    Uninstalling sqlite3.
    Uninstalling openssl.
    Uninstalling ca-certificates.
    Uninstalling perl.
    Uninstalling gdbm.
    Uninstalling bzip2.
    Uninstalling libffi.
    Uninstalling libexpat.
    Uninstalling readline.
    Uninstalling ncurses.
    Uninstalling zlib.
    Uninstalling patch.
    Uninstalling xz-utils.
    Unused options for buildout: 'allowed-eggs-from-site-packages' 'exec-sitecustomize' 'include-site-packages' 'unzip'.
    Installing xz-utils.
    ...
    Stripping binaries ...
    Done.
    slapos.rebootstrap:
    ************ REBOOTSTRAP: IMPORTANT NOTICE ************
    bin/buildout is being reinstalled right now, as new python:
      /srv/slapgrid/slappart1/srv/testnode/bsu/soft/90adf14823b5e2bc7dd89ccfbd9388df/parts/python3.5/bin/python3.5
    is available, and buildout is using another python:
      /opt/slapgrid/b9f9e0967ab8491759399f306d65239a/parts/python2.7/bin/python2.7
    Buildout will be restarted automatically to have this change applied.
    ************ REBOOTSTRAP: IMPORTANT NOTICE ************

    Uninstalling template.
    ...
    Uninstalling m4.
    Unused options for buildout: 'allowed-eggs-from-site-packages' 'exec-sitecustomize' 'include-site-packages' 'unzip'.
    Updating xz-utils.
    ...
    Updating python3.5.
    Installing m4.
    ...

About the implementation, we could merely add a `if not os.path.exists(...):`.
I fear cases where a previous run may have left bin/buildout in a non-working
state, so I suggest the use of a marker to force bootstrap if a previous run
failed whereas the existing bin/buildout was reused.

/reviewed-on nexedi/slapos.core!54

slapos_subscription_request: Rework subscription to consider that it is a second subscription of a user

Don't set email as login too soon, this is a task for later.

We intent to cancel the subscription and it's invoice.

Make it similar to ordering/delivery process.

The mensage should be improved.

The user is the Assigne of it's login objects, this allows the user manage their login configurations.

Do not run this script on production unless you know what you are doing.

Do not run this script when reindexation is occurring.

slapos_erp5: [Administration] Add script for updateRoleMapping only at the portal types that contains Roles.

This is script for SlapOS Master

The Owner is not assignee anymore, only the destination_section of the hosting subscription.

  Configure in a way that KVM can use be set with real IPv6 inside provided by slapos.

destination_section could not be set, so the role was never used.

/reviewed-on !52

  This allow during a subscription process, create a user and them create all
  documents using that user w/o rely on proxy roles (keeping good ownership
  across the documents).

  slapos_erp5: release new security with local_role_group_id
  slapos_cloud: include more security_uids columns
  slapos_cloud: set extra security_uids configuration.
  slapos_erp5: Remove duplicated entry on roles
  slapos_erp5: Assignee on [Software/Slave] Instance comes from the Hosting Subscription
  slapos_configurator: erp5_security_uid_innodb_catalog is installed now.
  slapos_erp5: Software Installation, Owner shoulnd't be the Assignee but the Requester.
  slapos_erp5: Update RoleSecurity Tests
  slapos_cloud: testSlapOSCloudWorkflow, New security requires Slave Instance be linked to a HS
  slapos_erp5: R-SHADOW-PERSON is only present on Payments w/o Destination Section