use sh as default unix shell, not bash

PR-URL: #2067
Credit: @isaacs
Close: #2067
Reviewed-by: @nlf

Author: isaacs

lib/utils/config.js

@@ -21,7 +21,7 @@ const editor = process.env.EDITOR ||
   (isWindows ? 'notepad.exe' : 'vi')
 
 const shell = isWindows ? process.env.ComSpec || 'cmd'
-  : process.env.SHELL || 'bash'
+  : process.env.SHELL || 'sh'
 
 const { tmpdir, networkInterfaces } = require('os')
 const getLocalAddresses = () => {

test/lib/utils/config.js

@@ -138,7 +138,7 @@ t.test('no shell on posix', t => {
     '@npmcli/ci-detect': () => false,
     '../../../lib/utils/is-windows.js': false
   })
-  t.equal(config.defaults.shell, 'bash')
+  t.equal(config.defaults.shell, 'sh')
   t.end()
 })