Apply suggestions from Michael's code review

Co-authored-by: Michael Chirico <[email protected]>

Author: jangorecki

NEWS.md

@@ -6,13 +6,13 @@
 
 ### BREAKING CHANGE
 
-1. Rolling functions `frollmean` and `frollsum` used to treat `Inf` and `-Inf` as `NA` when using default `algo="fast"`. It has been changed now and infinite values are not treated as `NA` anymore. If your input into those functions has `Inf` or `-Inf` then you will be affected by this change. As a result, argument that controls behavior of `NA`s has been renamed from `hasNA` to `has.nf` (_has non-finite_), as of 1.18.0 both will work, former with a warning.
+1. Rolling functions `frollmean` and `frollsum` distinguish `Inf`/`-Inf` from `NA` to match the same rules as base R when `algo="fast"` (previously they were considered the same). If your input into those functions has `Inf` or `-Inf` then you will be affected by this change. As a result, the argument that controls the handling of `NA`s has been renamed from `hasNA` to `has.nf` (_has non-finite_). `hasNA` continues to work with a warning, for now.
     ```r
     ## before
     frollsum(c(1,2,3,Inf,5,6), 2)
     #[1] NA  3  5 NA NA 11
 
-    ## 1.18.0
+    ## now
     frollsum(c(1,2,3,Inf,5,6), 2)
     #[1]  NA   3   5 Inf Inf  11