Bugfixes

• Containerize: accommodate nested or pre-existing spack-env paths (#41558)
• Fix setup-env script, when going back and forth between instances (#40924)
• Fix using fully-qualified namespaces from root specs (#41957)
• Fix a bug when a required provider is requested for multiple virtuals (#42088)
• OCI buildcaches:
  • only push in parallel when forking (#42143)
  • use pickleable errors (#42160)
• Fix using sticky variants in externals (#42253)
• Fix a rare issue with conditional requirements and multi-valued variants (#42566)

Package updates

• rust: add v1.75, rework a few variants (#41161,#41903)
• py-transformers: add v4.35.2 (#41266)
• mgard: fix OpenMP on AppleClang (#42933)