[Rd] small bug on qchisq (PR#6442)

[Remy.Drouilhet at upmf-grenoble.fr]

Full_Name: Drouilhet Rémy
Version: 1.8.1
OS: Linux
Submission from: (NULL) (195.221.43.136)


qchisq(1,10) works well but qchisq(1,10,ncp=0) does not work whereas ncp=0 is
the default value of the function qchisq(1,10). (of course, 10 will be replaced
by any integer value).
Let us notice that this bug occurs only when applying probability one.
(qchisq(seq(0,.9,.1),10,ncp=0) works very well).