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