Adds Sys.unsetenv() to default_undesirable_functions (#2192)

* Adds `Sys.unsetenv()` to `default_undesirable_functions`

closes #1762

* Update NEWS.md

NEWS.md

@@ -57,6 +57,7 @@
 * `unused_import_linter()` gains an argument `interpret_glue` (default `TRUE`) paralleling that in `object_usage_linter()` to toggle whether `glue::glue()` expressions should be inspected for exported object usage (#2042, @MichaelChirico).
 * `sort_linter()` only lints on `order()` of a single vector, excluding e.g. `x[order(x, y)]` and `x[order(y, x)]` (#2156, @MichaelChirico).
 * `redundant_ifelse_linter()` is aware of `dplyr::if_else()`'s `missing=` argument, so that `if_else(A, TRUE, FALSE, missing = FALSE)` doesn't lint, but `if_else(A, TRUE, FALSE, NA)` does (#1941, @MichaelChirico). Note that `dplyr::coalesce()` or `tidyr::replace_na()` may still be preferable.
+* `default_undesirable_functions` is updated to also include `Sys.unsetenv()` (#2192, @IndrajeetPatil).
 
 ### New linters
 

R/zzz.R

@@ -196,6 +196,7 @@ default_undesirable_functions <- all_undesirable_functions[names(all_undesirable
   "source",
   "Sys.setenv",
   "Sys.setlocale",
+  "Sys.unsetenv",
   "trace",
   "undebug",
   "untrace"