Bug in predict.lm?

Bert Gunter <gunter.berton <at> gene.com> writes:

Yes, I realize that it is more likely  a misunderstanding on my part.
Suitable humility will be tendered if this is pointed out.

The claimed "bug" is that predict.lm throws an error when the scale
argument is specified with interval = "conf" (and in some other
cases):

z <- lm(rnorm(10)~I(1:10))

predict(z,int="conf",scale=1)

Error in predict.lm(z, int = "conf", scale = 1) : object 'w' not found

R version 3.0.2 (2013-09-25)
Platform: i386-w64-mingw32/i386 (32-bit)

Cheers,
Bert

I do not see this (see below). 

Maybe traceback() or options(recover=browser) to get
to the bottom??

z <- lm(rnorm(10)~I(1:10))
predict(z,int="conf",scale=1)

fit        lwr       upr
1  0.02491723 -1.1270591 1.1768935
2  0.06402057 -0.9129873 1.0410284
3  0.10312392 -0.7185606 0.9248085
4  0.14222726 -0.5569958 0.8414504
5  0.18133060 -0.4477852 0.8104464
6  0.22043395 -0.4086818 0.8495497
7  0.25953729 -0.4396858 0.9587604
8  0.29864063 -0.5230439 1.1203252
9  0.33774398 -0.6392639 1.3147518
10 0.37684732 -0.7751290 1.5288236

version

_                           
platform       x86_64-apple-darwin10.8.0   
arch           x86_64                      
os             darwin10.8.0                
system         x86_64, darwin10.8.0        
status                                     
major          3                           
minor          0.2                         
year           2013                        
month          09                          
day            25                          
svn rev        63987                       
language       R                           
version.string R version 3.0.2 (2013-09-25)
nickname       Frisbee Sailing