Available fixes for 6.4.1 (May 10 2019)

The diff file backports-6.4.1.diff contains the fixes described below. Copy the file to the top directory of Quantum ESPRESSO and type the command

patch -p1 --merge < backports-6.4.1.git-diff

bad link to wannier90
variable-cell optimization with cell_dofree='z' wasn't working as expected
error in pp.x with num_plot=17 and spin polarization
Bug in spin-polarized meta-GGA (noticed by Shoaib Muhammad,
Sungkyunkwan U.)
Unphysical fractional translations (tau/n with n/=2,3,4,6) were not
explicitly discarded, thus leading in unfortunate cases to strange
values for FFT factors and grids. Also: if "nosym" is true, inversion
symmetry flag (invsym) and info on FFT factors (fft_fact) must also
be reset (problem spotted by Thomas Brumme, Leipzig)
PPACF wasn't working any longer in v.6.4 and 6.4.1 for nspin=2 and
for hybrid functionals (fixed by Yang Jiao, Chalmers)
option "write_unkg" of pw2wannier90.f90 wasn't working as expected
Input parameters (for restarting DFPT+U calculations) read_dns_bare
and d2ns_type were missing in the PH input namelist, and moreover
they were not broadcasted.

New in 6.4.1 branch :

A warning is issued if the lattice parameter seems to be a conversion
factor instead of a true lattice parameter. Conversion should be achieved
with the appropriate options, not with dirty tricks. In the future this
will no longer be allowed
A warning is issued if ibrav=0 is used for systems having symmetry. If not
properly done this may lead to strange problems with symmetry detection
and symmetrization. Lattice information should be used if available.

Two bugs fixed in HP: 1) the code was not working correctly when fractional
translations were present, 2) there was a bug in the case when either there
is only one k point, or when k pools are used and some of the pools have
only one k point.
Restart of ph.x with 2D boundary conditions has been fixed (see gitlab
issue #102)
XML file correctly written if tetrahedra are used (see gitlab issue #103)