By the way, here is a patch. I'll commit it.
best
Robert Dodier
PS.
$ git diff doc/info/Polynomials.texi
diff --git a/doc/info/Polynomials.texi b/doc/info/Polynomials.texi
index 4c376be..565750a 100644
--- a/doc/info/Polynomials.texi
+++ b/doc/info/Polynomials.texi
@@ -1446,7 +1446,8 @@ maintained as fully factored as possible without an actual call to the
factor package. This should always save space and may save some time
in some computations. The numerator and denominator are still made
relatively prime
-(e.g. @code{rat ((x^2 - 1)^4/(x + 1)^2)} yields @code{(x - 1)^4 (x + 1)^2)},
+(e.g., @code{rat((x^2 - 1)^4/(x + 1)^2)} yields @code{(x - 1)^4 (x + 1)^2}
+when @code{ratfac} is @code{true}),
but the factors within each part may not be relatively prime.
@code{ratprint} if @code{false} suppresses the printout of the message