The manpage for yacc(1) comes out slightly mangled, because, wherever it wants to talk about #line directives, the original file (/usr/man/man1/yacc.1) uses the text "\#line"; apparently the \ isn't sufficient to keep the # from acting as a comment, and troff chops off the rest of the line. To see the effect, look at the description of the "-l" option. I've seen other mangled manpages on RedHat, too; I don't remember now which ones they were, but I'll keep a lookout in the future to see if they're the same problem.
fixed in byacc-1.9-11 and later. thanks for the report.