bug : all emacs versions after 2016-02-14 are affected
all emacs pretests version are affected including today .93
25.0.92 and 93 are buggy , 25.0.91 is not

this is what :
fonts menlo very bad displaying = overlapping vertical line space 
(and other fonts mono i am told in irc chan )

by eyeballing changelogs i have compiled ii by using src/xftfont.c 
from pretest 25.0.91 version and it works just fine

scroll down at changelog line reading "2016-02-25" "Remove unneeded workaround in xftfont.c"

i guess it was needed :)
compiling .93 and latest git  by lamely overwrtiting src/xftfont.c from pretest  25.0.91 
fonts menlo are non overlapping anymore
all git version i have compiled after 2016-02-14 are affected