ARROW-3795: [R] Support for retrieving NAs from INT64 arrays

[romainfrancois]

library(arrow)
#> 
#> Attaching package: 'arrow'
#> The following object is masked from 'package:utils':
#> 
#>     timestamp
#> The following objects are masked from 'package:base':
#> 
#>     array, table

x <- bit64::as.integer64(c(NA))
a <- array(x)
a$as_vector()
#> integer64
#> [1] <NA>

^{Created on 2018-11-16 by the reprex package (v0.2.1.9000)}

[romainfrancois]

ping @javierluraschi

[wesm]

+1

[wesm]

* DONE (devtools)
The downloaded source packages are in
	‘/tmp/Rtmpe50Hvl/downloaded_packages’
4.32s$ Rscript -e 'deps <- devtools::dev_package_deps(dependencies = NA);devtools::install_deps(dependencies = TRUE);if (!all(deps$package %in% installed.packages())) { message("missing: ", paste(setdiff(deps$package, installed.packages()), collapse=", ")); q(status = 1, save = "no")}'
Error: HTTP error 403.
  API rate limit exceeded for 35.188.73.34. (But here's the good news: Authenticated requests get a higher rate limit. Check out the documentation for more details.)
  Rate limit remaining: 0
  Rate limit reset at: 2018-11-16 21:15:57 UTC
Execution halted

It would help give me peace of mind merging patches if I could easily run the unit test suite locally (preferably from the command line so I can add a bash function to my scripts). I opened https://issues.apache.org/jira/browse/ARROW-3824 about documenting this in the README

[romainfrancois]

Sure. Will document that. Is it possible to clear the travis cache as @jimhester hinted ? I don't have access so can't do it on the main repo.

[wesm]

Yes I'll try that now; there are a lot of caches!