Add getProjectPath() to compute path to parent project

Previously, process.cwd() did the job just fine but with node v8.1.2
(compared to 7.10.0 at least) the output has changed. So, use the
following hack: when installing a node package, npm adds it to PATH.
Since we know:
a) the suffix of that path entry (commitplease/node_modules/.bin)
b) the fact that the other project is installing commitplease

then find that entry and use its prefix as parent project path

Refs: jquery/jquery#3708

Author: Alexander Lisianoi

index.js

@@ -10,9 +10,37 @@ var validate = require('./lib/validate')
 var sanitize = require('./lib/sanitize')
 var defaults = require('./lib/defaults')
 
+// Need to find the path to the project that is installing
+// commitplease. Previously, process.cwd() made the job easy but its
+// output changed with node v8.1.2
+function getProjectPath () {
+  // Use the fact that npm will inject a path that ends with
+  // commitplease/node_modules/.bin into PATH
+  var p = process.env.PATH.split(':').filter(
+    function (p) {
+      return p.endsWith(path.join('commitplease', 'node_modules', '.bin'))
+    }
+  )
+
+  if (p.length !== 1) {
+    console.error(chalk.red('Failed to find project path\n'))
+  }
+
+  // Removing suffix node_modules/commitplease/node_modules/.bin will
+  // give the absolute path to the project root
+  p = p[0].split(path.sep)
+  p = p.slice(0, p.length - 4)
+
+  return path.sep + p.join(path.sep)
+}
+
 function getOptions () {
-  var pkg = path.join(process.cwd(), 'package.json')
-  var npm = path.join(process.cwd(), '.npmrc')
+  var projectPath = getProjectPath()
+
+  console.log(projectPath)
+
+  var pkg = path.join(projectPath, 'package.json')
+  var npm = path.join(projectPath, '.npmrc')
 
   pkg = fs.existsSync(pkg) && require(pkg) || {}
   npm = fs.existsSync(npm) && ini.parse(fs.readFileSync(npm, 'utf8')) || {}