[Rd] R fails to build on AFS (PR#6488)

[Atro.Tossavainen+rproject at helsinki.fi]

Full_Name: Atro Tossavainen
Version: 1.8.1
OS: Linux x86, PPC, Solaris 7 SPARC, IRIX 6.5, Tru64 4.0F, HP-UX 10.20
Submission from: (NULL) (128.214.205.5)


The @ character in path names causes the R build process to barf.

It is used on the AFS file system for OS-specific magic:

/afs/../../../../@sys/../.. links to a different directory on each system
type (the magic "@sys" is expanded by AFS at file access time to the
system value, such as alpha_dux40, hp_ux102, i386_linux24, etc).