[R-pkg-team] Bug#962280: r-cran-gwidgetstcltk autopkgtest failures: "xvfb-run: error: Xvfb failed to start"

[Olivier Tilloy]

Package: r-cran-gwidgetstcltk
Version: 0.0-55.1-2
Severity: normal

Dear Maintainer,

r-cran-gwidgetstcltk is more often than not failing its autopkgtests with the following error:

    BEGIN TEST runRUnit.R
    xvfb-run: error: Xvfb failed to start

(see https://ci.debian.net/packages/r/r-cran-gwidgetstcltk/).

This appears to be caused by the test script iterating over a list of test files and spawning xvfb-run for each of them, without waiting for the previous instance to clean up after itself, thus often resulting in the server number not being free. Passing "-a" to xvfb-run (to get a free server number for each instance) appears to fix the problem reliably.