After further investigation using strace, I came to the conclusion that
this is in fact the same as bug #542361 (libgamin too buggy to Provide
libfam):
$ strace okular
[...]
socket(PF_FILE, SOCK_STREAM, 0) = 11
connect(11, {sa_family=AF_FILE, path=@"/tmp/fam-sqrt-"}, 110
^C <unfinished ...>
Therefore, I think this issue can be merged into #542361.