* subversion/libsvn_fs_fs/cached_data.c
  (svn_fs_fs__rep_chain_length): Document the pool usage / cleanup strategy
                                 No functional change.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1627947 13f79535-47bb-0310-9956-ffa450edef68
Make sure the svn_fs_t remains valid after calls to svn svn_fs_upgrade.

If we make the creation of cache instances contingent upon the initial
FS format, those instances will not be available after the FS upgrade.
And if those cache instances are mandatory with the new format, we may
segfault.

* subversion/libsvn_fs_fs/caching.c
  (svn_fs_fs__initialize_caches): Always create all cache instances that
                                  are mandatory for some FS format even if
                                  the current format would not need them.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1627948 13f79535-47bb-0310-9956-ffa450edef68