Subrepositories let you nest external repositories or projects into a
    parent Mercurial repository, and make commands operate on them as a group.

    Mercurial currently supports Mercurial, Git, and Subversion

    Subrepositories are made of three components:

    1. Nested repository checkouts. They can appear anywhere in the parent
       working directory.
    2. Nested repository references. They are defined in ".hgsub" and tell
       where the subrepository checkouts come from. Mercurial subrepositories
       are referenced like:

         path/to/nested =

       Git and Subversion subrepos are also supported:

         path/to/nested = [git]git://
         path/to/nested = [svn]

       where "path/to/nested" is the checkout location relatively to the
       parent Mercurial root, and "" is
       the source repository path. The source can also reference a filesystem

       Note that ".hgsub" does not exist by default in Mercurial repositories,
       you have to create and add it to the parent repository before using

    3. Nested repository states. They are defined in ".hgsubstate" and capture
       whatever information is required to restore the subrepositories to the
       state they were committed in a parent repository changeset. Mercurial
       automatically record the nested repositories states when committing in
       the parent repository.

          The ".hgsubstate" file should not be edited manually.

    Adding a Subrepository

    If ".hgsub" does not exist, create it and add it to the parent repository.
    Clone or checkout the external projects where you want it to live in the
    parent repository. Edit ".hgsub" and add the subrepository entry as
    described above. At this point, the subrepository is tracked and the next
    commit will record its state in ".hgsubstate" and bind it to the committed

    Synchronizing a Subrepository

    Subrepos do not automatically track the latest changeset of their sources.
    Instead, they are updated to the changeset that corresponds with the
    changeset checked out in the top-level changeset. This is so developers
    always get a consistent set of compatible code and libraries when they

    Thus, updating subrepos is a manual process. Simply check out target
    subrepo at the desired revision, test in the top-level repo, then commit
    in the parent repository to record the new combination.

    Deleting a Subrepository

    To remove a subrepository from the parent repository, delete its reference
    from ".hgsub", then remove its files.

    Interaction with Mercurial Commands

    add           add does not recurse in subrepos unless -S/--subrepos is
                  specified.  However, if you specify the full path of a file
                  in a subrepo, it will be added even without -S/--subrepos
                  specified. Git and Subversion subrepositories are currently
                  silently ignored.
    archive       archive does not recurse in subrepositories unless
                  -S/--subrepos is specified.
    commit        commit creates a consistent snapshot of the state of the
                  entire project and its subrepositories. If any
                  subrepositories have been modified, Mercurial will abort.
                  Mercurial can be made to instead commit all modified
                  subrepositories by specifying -S/--subrepos, or setting
                  "ui.commitsubrepos=True" in a configuration file (see "hg
                  help config").  After there are no longer any modified
                  subrepositories, it records their state and finally commits
                  it in the parent repository.
    diff          diff does not recurse in subrepos unless -S/--subrepos is
                  specified. Changes are displayed as usual, on the
                  subrepositories elements. Git and Subversion subrepositories
                  are currently silently ignored.
    forget        forget currently only handles exact file matches in
                  subrepos. Git and Subversion subrepositories are currently
                  silently ignored.
    incoming      incoming does not recurse in subrepos unless -S/--subrepos
                  is specified. Git and Subversion subrepositories are
                  currently silently ignored.
    outgoing      outgoing does not recurse in subrepos unless -S/--subrepos
                  is specified. Git and Subversion subrepositories are
                  currently silently ignored.
    pull          pull is not recursive since it is not clear what to pull
                  prior to running "hg update". Listing and retrieving all
                  subrepositories changes referenced by the parent repository
                  pulled changesets is expensive at best, impossible in the
                  Subversion case.
    push          Mercurial will automatically push all subrepositories first
                  when the parent repository is being pushed. This ensures new
                  subrepository changes are available when referenced by top-
                  level repositories.  Push is a no-op for Subversion
    status        status does not recurse into subrepositories unless
                  -S/--subrepos is specified. Subrepository changes are
                  displayed as regular Mercurial changes on the subrepository
                  elements. Subversion subrepositories are currently silently
    update        update restores the subrepos in the state they were
                  originally committed in target changeset. If the recorded
                  changeset is not available in the current subrepository,
                  Mercurial will pull it in first before updating.  This means
                  that updating can require network access when using

    Remapping Subrepositories Sources

    A subrepository source location may change during a project life,
    invalidating references stored in the parent repository history. To fix
    this, rewriting rules can be defined in parent repository "hgrc" file or
    in Mercurial configuration. See the "[subpaths]" section in hgrc(5) for
    more details.