Problem installing `later` package from GitHub

With latest packrat, installing later from GitHub fails... not sure if something weird is going on with later (other packages from GitHub seem to work fine) or packrat... I have been able to reproduce this on several machines, as well as interactively... the weird thing is that running the build again does successfully extract the tarball and install the package. Which makes me feel like packrat may be the issue.

Installing later (0.7.5.9000) ...
Failed to extract archive:
- '/home/bobo/proj/packrat/src/later/2fb214b73e0d8df355dc5ec1989226774c81e4fa.tar.gz' => '/tmp/RtmpgtiEk1'
Reason: character argument expected

Error in if (!file.exists(file.path(pkg_path, "DESCRIPTION"))) { :
  argument is of length zero

Reproducible lockfile (sorry for the old version of R... hopefully that's not the culprit - it just happens to be what I had on hand at the time):

PackratVersion: 0.5.0
RVersion: 3.2.3
Repos: CRAN=https://cloud.r-project.org

Package: BH
Source: CRAN
Version: 1.66.0-1
Hash: 4cc8883584b955ed01f38f68bc03af6d

Package: Rcpp
Source: CRAN
Version: 1.0.0
Hash: c7273c0f0bc9f5e41f4c52a8cf571f0f

Package: later
Source: github
Version: 0.7.5.9000
Hash: b526f1546622b3dfcd90b04487022880
Requires: BH, Rcpp, rlang
GithubRepo: later
GithubUsername: r-lib
GithubRef: master
GithubSha1: 2fb214b73e0d8df355dc5ec1989226774c81e4fa
RemoteHost: api.github.com
RemoteRepo: later
RemoteUsername: r-lib
RemoteRef: master
RemoteSha: 2fb214b73e0d8df355dc5ec1989226774c81e4fa

Package: packrat
Source: CRAN
Version: 0.5.0
Hash: 498643e765d1442ba7b1160a1df3abf9

Package: rlang
Source: CRAN
Version: 0.3.0.1
Hash: 35fb7a51d5d756c56f793ed9c381fb84

R 3.5.1 fails with:

Installing later (0.7.5.9000) ... 
FAILED
Error in getSourceForPkgRecord(pkgRecord, srcDir(project), availablePackagesSource(repos = repos),  : 
  Failed to download package from URL:
- 'api.github.com/repos/r-lib/later/tarball/2fb214b73e0d8df355dc5ec1989226774c81e4fa'

Struggling to understand all of this 😮 It may be possible that api.github.com has weird things going on? I'm getting some interesting results curling that URL

I can reproduce this on two systems (both xenial), and cannot on two other systems (both trusty, I think?).

Start by reproducing the failure with the supplied Packrat lockfile on R 3.2.3 and R 3.5.1, using the GitHub tarball URL for r-lib/later. Compare the archive download and extraction steps on the Xenial systems where it fails with the systems where it succeeds, including the successful second build. Done means identifying whether Packrat or api.github.com causes the failure and documenting a reliable fix or narrowed cause.