Try packages amelie or autoencoder (just the first two I stumbled upon)

Try R2spec --verbose --debug --no-check --no-suggest -p autoencoder
(amelie has exactly the same problem)

steuer@gaia:~/rpmbuild/SOURCES> R2spec --verbose --debug --no-check --no-suggest -p autoencoder
INFO:R2spec:Package found in : http://cran.r-project.org/src/contrib/PACKAGES
INFO:R2spec:Sources are already present, no need to re-download
INFO:R2spec:Opening: /home/steuer/rpmbuild/SOURCES/autoencoder_1.1.tar.gz
INFO:R2spec:Loading "autoencoder/DESCRIPTION"
INFO:R2spec:Determining if the package is arch dependant or not
INFO:R2spec:Package is not arch dependant
INFO:R2spec:Removing extracted sources: "autoencoder"
INFO:R2spec:Filling spec variable from info collected

here it hangs

^CTraceback (most recent call last):
File "/usr/bin/R2spec", line 29, in <module>
R2spec().main(ARG)
File "/usr/lib/python2.7/site-packages/r2spec/r2spec_obj.py", line 285, in main
spec.fill_spec_info()
File "/usr/lib/python2.7/site-packages/r2spec/spec.py", line 170, in fill_spec_info
self.package.get('Description'))
File "/usr/lib/python2.7/site-packages/r2spec/spec.py", line 38, in format_description
while cnt < len(description) and char < description.rfind(" "):
KeyboardInterrupt

The file looks innocent to me.