Fix ActivePlan::number_of_mutators

Updated the `ruby` repo revision to fix a bug where the number of
mutators returned from `ActivePlan::number_of_mutators` does not match
the number of mutators returned from `ActivePlan::mutators`.

Also updated the `mmtk-core` repo revision.  More assertions are added
so that such bugs can be detected earlier.

mmtk-core PR: mmtk/mmtk-core#1182
ruby PR: mmtk/ruby#84

Fixes: mmtk#84

mmtk/Cargo.toml

@@ -12,7 +12,7 @@ edition = "2021"
 # Metadata for the Ruby repository
 [package.metadata.ci-repos.ruby]
 repo = "mmtk/ruby" # This is used by actions/checkout, so the format is "owner/repo", not URL.
-rev = "1d3f79843ef8dafa90664b18a24d4b337a4e5117"
+rev = "8082532b9f720a1e7508ac32641dcfbbf51dd518"
 
 [lib]
 name = "mmtk_ruby"
@@ -36,8 +36,8 @@ probe = "0.5"
 features = ["is_mmtk_object", "object_pinning", "sticky_immix_non_moving_nursery"]
 
 # Uncomment the following lines to use mmtk-core from the official repository.
-git = "https://github.com/mmtk/mmtk-core.git"
-rev = "f9b85bca5b1ae530854e09d553f3020edde46cdb"
+git = "https://github.com/wks/mmtk-core.git"
+rev = "b4ed92905fb1218692170374cb6ee5b23b239a5e"
 
 # Uncomment the following line to use mmtk-core from a local repository.
 # path = "../../mmtk-core"