According to the help, if parameter -w is not set, the width is set to 50% by default "like period; defaults to 50% period". Unfortunately, it is always set to 1us.

In the below example, the pulse width is set to 1us, not to 50ns

$ fmc-fdelay-pulse -d 0x12 -v -o 1 -T 100n
Parsed times:
  start time:        1941:000,000,000,000 ps
  pulse width:          0:000,001,000,000 ps
  period:               0:000,000,100,000 ps
Channel 1: pulse generator mode
  start at:               1941:000,000,000,000 ps
  pulse width:               0:000,001,000,000 ps
  repeat:                    infinite
  period:                    0:000,000,100,000 ps

$ fmc-fdelay-pulse -h
   -d <dev>        device ID (hexadecimal)
   -o <output>     ouput channel: 1..4 (default 1)
   -c <count>      default is 0 and means forever
   -m <mode>       "pulse" (default), "delay", "disable"
   -r <reltime>    relative time,  e.g. "10m+20u" -- use m,u,n,p and add/sub
   -D <date>       absolute time, <secs>:<nano>
   -T <period>     period, e.g. "50m-20n" -- use m,u,n,p and add/sub
   -w <width>      like period; defaults to 50% period
   -t              wait for trigger before exiting
   -p              pulse per seconds (sets -D -T -w)
   -1              10MHz (sets -D -T -w)
   -v              verbose (report action)

This bug does not fail python tests.