For several years now Mercurial has had bookmarks in core, which are analogous to git's local branches.
It's also worth pointing out that many of the extensions you referred to (rebase, shelve) are bundled with core Mercurial and need only a one-line addition to a configuration file to turn them on. Extensions bundled with core Mercurial have the same level support and backward compatibility guarantees as the rest of Mercurial. Part of Mercurial's command line philosophy is to not include obvious foot-guns (like the ability to rewrite history) in the default version.
It's quite easy to build mercurial from source. That said I understand the pain of being on locked down ancient linux installs with no access to compilers.
It's also worth pointing out that many of the extensions you referred to (rebase, shelve) are bundled with core Mercurial and need only a one-line addition to a configuration file to turn them on. Extensions bundled with core Mercurial have the same level support and backward compatibility guarantees as the rest of Mercurial. Part of Mercurial's command line philosophy is to not include obvious foot-guns (like the ability to rewrite history) in the default version.