run-script: change default for --scripts-prepend-node-path to `warn…

…-only`

Change the default behaviour of npm to never prepending the
current node executable’s directory to `PATH` but printing a warning
in the cases in which it previously did.

PR-URL: npm/npm#13409
Credit: @addaleax
Reviewed-By: @zkat
Reviewed-By: @othiym23

doc/cli/npm-run-script.md

@@ -41,9 +41,11 @@ you should write:
 instead of `"scripts": {"test": "node_modules/.bin/tap test/\*.js"}` to run your tests.
 
 `npm run` sets the `NODE` environment variable to the `node` executable with
-which `npm` is executed. Also, the directory within which it resides is added to the
-`PATH`, if the `node` executable is not in the `PATH`. This behaviour can be
-overridden by running `npm` with the `--scripts-prepend-node-path` flag.
+which `npm` is executed. Also, if the `--scripts-prepend-node-path` is passed,
+the directory within which `node` resides is added to the
+`PATH`. If `--scripts-prepend-node-path=auto` is passed (which has been the
+default in `npm` v3), this is only performed when that `node` executable is
+not found in the `PATH`.
 
 If you try to run a script without having a `node_modules` directory and it fails,
 you will be given a warning to run `npm install`, just in case you've forgotten.

doc/misc/npm-config.md

@@ -812,7 +812,7 @@ of packages specified according to the pattern `@organization/package`.
 
 ### scripts-prepend-node-path
 
-* Default: "auto"
+* Default: "warn-only"
 * Type: Boolean, `"auto"` or `"warn-only"`
 
 If set to `true`, add the directory in which the current `node` executable

lib/config/defaults.js

@@ -193,7 +193,7 @@ Object.defineProperty(exports, 'defaults', {get: function () {
     'save-optional': false,
     'save-prefix': '^',
     scope: '',
-    'scripts-prepend-node-path': 'auto',
+    'scripts-prepend-node-path': 'warn-only',
     searchopts: '',
     searchexclude: null,
     searchstaleness: 15 * 60,