Something in selfrando is totally braindamaged.

Reported on the blog at: https://blog.torproject.org/comment/269741#comment-269741

Root cause:

openat(AT_FDCWD, "/proc/self/environ", O_RDONLY) = -1 ENOENT (No such file or directory)
read(-2, 0x7ffc35bb47e0, 32)            = -1 EBADF (Bad file descriptor)
read(-2, 0x7ffc35bb47e0, 32)            = -1 EBADF (Bad file descriptor)
read(-2, 0x7ffc35bb47e0, 32)            = -1 EBADF (Bad file descriptor)
read(-2, 0x7ffc35bb47e0, 32)            = -1 EBADF (Bad file descriptor)
read(-2, 0x7ffc35bb47e0, 32)            = -1 EBADF (Bad file descriptor)
read(-2, 0x7ffc35bb47e0, 32)            = -1 EBADF (Bad file descriptor)
read(-2, 0x7ffc35bb47e0, 32)            = -1 EBADF (Bad file descriptor)
read(-2, 0x7ffc35bb47e0, 32)            = -1 EBADF (Bad file descriptor)

... (repeat ad infinitum)

So, fallout from #20773 (closed).