Here is a positive test result for HDF5 release 1.10.1-pre2. With HDF5 1.10.0 (and patch1) on Mac OS, all access to NFSv3-mounted files would fail due to the previously reported flock problem. In plainer terms, HDF5 1.10.0 was not able to read or write any files on network file servers. This was due to a deficiency in NFSv3 support for Mac OS.
This problem was solved in 1.10.1 pre-releases. HDF5 support added a fix that disabled file locking behavior, thus avoiding the problem. Please see details in the release notes starting with 1.10.1-pre2, under "Other New Features".
The fix is not a build fix, rather it is a run time environment variable setting. This is versatile. File locking can be used with local files, and disabled only when necessary to access network files.
On a more mundane note, HDF5 1.10.1-pre2 compiled and passed all make check tests on my desktop Mac, OS X El Capitan version 10.11.6.
Thanks to the HDF5 Group for providing the flock fix. This will allow my work group and other Mac users to advance past HDF5 1.8.