v1.8.7 is a bug fix release, primarily driven by discovery of a significant memory leak. All users are encouraged to upgrade to v1.8.7 when possible.

** NOTE: v1.8.7 technically breaks ABI with prior versions ** in the 1.8 series because it repairs two incorrect API ** signatures. However, users will only need to recompile ** if they were using those functions - which they couldn't ** have been, because the signatures were wrong :-) - Plugged a memory leak that impacted blocking sends - Fixed incorrect declaration for MPI_T_pvar_get_index and added missing return code MPI_T_INVALID_NAME. - Fixed an uninitialized variable in PMI2 support - Added new vendor part id for Mellanox ConnectX4-LX - Fixed NBC_Copy for legitimate zero-size messages - Fixed MPI_Win_post and MPI_Win_start for zero-size messages - Protect the OOB ports from segfaulting when accessed by port scanners - Fixed several Fortran typos - Fixed configure detection of XRC support - Fixed support for highly heterogeneous systems to avoid memory corruption when printing out the bindings