Travis CI问题-无法检索gpg密钥

Travis CI在构建一个R包时失败，出现了我以前从未见过的错误，并且似乎与未检索到的gpg密钥有关（而不是代码中的典型错误：）

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更多关于Travis的信息

我也遇到了以前从未见过的问题。我今天早上重新启动了构建，它完成时没有任何问题。可能是间歇性的问题。

Installing R
0.46s$ sudo add-apt-repository "deb http://cloud.r-project.org/bin/linux/ubuntu $(lsb_release -cs)/"
60.08s$ sudo apt-key adv --keyserver ha.pool.sks-keyservers.net --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9
Executing: /tmp/tmp.Cp93xmp8GR/gpg.1.sh --keyserver
ha.pool.sks-keyservers.net
--recv-keys
E298A3A825C0D65DFD57CBB651716619E084DAB9
gpg: requesting key E084DAB9 from hkp server ha.pool.sks-keyservers.net
gpgkeys: key E298A3A825C0D65DFD57CBB651716619E084DAB9 can't be retrieved
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
The command "sudo apt-key adv --keyserver ha.pool.sks-keyservers.net --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9" failed and exited with 2 during .
Your build has been stopped.