fix(parse): make parse return a 'deep' clone

Author: louis-bompart

Diff for: functions/parse.js

@@ -7,7 +7,7 @@ const parse = (version, options) => {
   options = parseOptions(options)
 
   if (version instanceof SemVer) {
-    return version
+    return new SemVer(version.version)
   }
 
   if (typeof version !== 'string') {

Diff for: test/functions/parse.js

@@ -11,8 +11,15 @@ t.test('returns null instead of throwing when presented with garbage', t => {
 
 t.test('parse a version into a SemVer object', t => {
   t.match(parse('1.2.3'), new SemVer('1.2.3'))
-  const s = new SemVer('4.5.6')
-  t.equal(parse(s), s, 'just return it if its a SemVer obj')
+  const inputSemVer = new SemVer('4.5.6')
+  const parsedSemVer = parse(inputSemVer)
+  t.equal(
+    JSON.stringify(parse(inputSemVer)),
+    JSON.stringify(inputSemVer),
+    'returns a copy if input is a SemVer obj'
+  )
+  inputSemVer.version = '4.5.7'
+  t.equal(parsedSemVer.version, '4.5.6', 'is a deep clone when input is a SemVer obj')
   const loose = new SemVer('4.2.0', { loose: true })
   t.match(parse('4.2.0', true), loose, 'looseness as a boolean')
   t.match(parse('4.2.0', { loose: true }), loose, 'looseness as an option')