Without this change, any failed assertion in the second (or a later) test
inside a test suite has a chance of double deleting memory, resulting in
a heap corruption. See #1096 for details.
This leaves alone the test cases where we "just" use cl_git_sandbox_init()
and cl_git_sandbox_cleanup(). These methods already take good care to not
double delete a repository.
Fixes#1096
This expands the types of peeling that `git_object_peel` knows
how to do to include TAG -> BLOB peeling, and makes the errors
slightly more consistent depending on the situation. It also
adds a new special behavior where peeling to ANY will peel until
the object type changes (e.g. chases TAGs to a non-TAG).
Using this expanded peeling, this replaces peeling code that was
embedded in `git_tag_peel` and `git_reset`.
