data.table's fread() giving unwanted download message

Question

I'm not too familiar with data.table's fread function, but it makes quick work of reading my data, so now I'm intrigued. At URL "http://www.retrosheet.org/CurrentNames.csv", there is a simple csv file. The following two calls work fine.

readLines("http://www.retrosheet.org/CurrentNames.csv", n = 2)
# [1] "ANA,LAA,AL,,Los Angeles,Angels,,4/11/1961,9/1/1965,Los Angeles,CA"
# [2] "ANA,CAL,AL,,California,Angels,,9/2/1965,9/29/1968,Anaheim,CA"
rcsv <- read.csv("http://www.retrosheet.org/CurrentNames.csv", header = FALSE)

But fread is delivering a download message, and I can't seem to turn it off with

showProgress = FALSE

I could use suppressMessages(), but I don't really want to.

library(data.table)
dtf <- fread("http://www.retrosheet.org/CurrentNames.csv", 
             header = FALSE, showProgress = FALSE)
# trying URL 'http://www.retrosheet.org/CurrentNames.csv'
# Content type 'text/plain' length 7729 bytes
# opened URL
# ==================================================
# downloaded 7729 bytes

Can anyone explain this, and can I turn it off in the fread arguments?

It looks like a call to download.file has occurred somewhere. Why wouldn't fread just read the URL the same way as read.csv?

Answer 1

Update Oct 2014. Now in v1.9.5 :

fread now passes showProgress=FALSE through to download.file() as quiet=!showProgress. Thanks to a pull request from Karl Broman and Richard Scriven for filing the issue, #741.

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Previous answer ...

It does download the file, here is the part of the code that does it.

else if (substring(input, 1, 7) %chin% c("http://", "https:/", 
    "file://")) {
    tt = tempfile()
    on.exit(unlink(tt), add = TRUE)
    download.file(input, tt)
    input = tt
}

My guess this is because fread makes more than one pass at the file, first to get the structure, then to actually read the whole thing in. Saves downloading multiple times.