Commits
Merging in latest from upstream (HDFFV/hdf5:refs/heads/develop) * commit 'fa829e322ed44a67e2b3f2d6adf1306ad794859b': Fix non-threadsafe API context head pointer handling.
Merging in latest from upstream (HDFFV/hdf5:refs/heads/develop) * commit 'fa829e322ed44a67e2b3f2d6adf1306ad794859b': Fix non-threadsafe API context head pointer handling.