Regain compatibility with 'package' objects in load_all()

This was broken when we changed pkgload::load_all() to take a path
rather than a package object.

Fixes r-lib#1923

NEWS.md

@@ -1,5 +1,8 @@
 # devtools 2.0.1.9000 - Development
 
+* `load_all()` now accepts 'package' objects, regaining previous behavior in
+  devtools prior to 2.0.0 (#1923)
+
 * `test()`, `test_coverage()` and `test_coverage_file()` now set the
   `TESTTHAT_PKG` environment variable, so it is more consistent with running
   the tests during `R CMD check` (testthat#787).

R/pkgload.R

@@ -3,6 +3,11 @@
 #' @export
 load_all <- function(path = ".", reset = TRUE, recompile = FALSE,
                      export_all = TRUE, helpers = TRUE, quiet = FALSE, ...) {
+
+  if (inherits(path, "package")) {
+    path <- path$path
+  }
+
   save_all()
 
   pkgload::load_all(