[Rd] help.start() and Debian packaging (PR#8483)

[greg.kochanski@phon.ox.ac.uk]

Full_Name: Greg Kochanski
Version: 2.2.0
OS: Debian Linux on i686
Submission from: (NULL) (212.159.16.190)


Debian packages the R documentation separately from the R core code.
Consequently, it is possible for people to have R without
the HTML documentation.   (In fact, the docs are not installed by default,
so it's very likely.)


Thus, help.start() cannot depend on the HTML documentation being there.
It should check for one (or a few) files and produce some reasonable
error message if it is not there.   Maybe something like
"Warning: the HTML documentation is not installed."

Alternatively, help.start() could produce references to some on-line
HTML documentation, instead of local documentation.



A related bug is that if one calls
help.start()  when the HTML documentation does not exist,
all future calls to help() will lead to errors.