Merge branch 'jk/commit-graph-leak-fixes'

Merge branch 'jk/commit-graph-leak-fixes'

Leakfix.

* jk/commit-graph-leak-fixes:
  commit-graph: clear oidset after finishing write
  commit-graph: free write-context base_graph_name during cleanup
  commit-graph: free write-context entries before overwriting
  commit-graph: free graph struct that was not added to chain
  commit-graph: delay base_graph assignment in add_graph_to_chain()
  commit-graph: free all elements of graph chain
  commit-graph: move slab-clearing to close_commit_graph()
  merge: free result of repo_get_merge_bases()
  commit-reach: free temporary list in get_octopus_merge_bases()
  t6700: mark test as leak-free