fix(npm): filter out package-lock = false in .npmrc

This prevents us from updating npm lock files

lib/manager/npm/extract/index.js

@@ -66,6 +66,10 @@ async function extractDependencies(content, packageFile, config) {
     npmrc = await platform.getFile(
       upath.join(path.dirname(packageFile), '.npmrc')
     );
+    if (npmrc && npmrc.includes('package-lock')) {
+      logger.info('Stripping package-lock setting from npmrc');
+      npmrc = npmrc.replace(/(^|\\n)package-lock.*?(\n|$)/g, '');
+    }
     if (npmrc) {
       if (
         npmrc.includes('=${') &&

test/manager/npm/extract/index.spec.js

@@ -76,6 +76,20 @@ describe('manager/npm/extract', () => {
       );
       expect(res).toMatchSnapshot();
     });
+    it('finds and filters .npmrc', async () => {
+      platform.getFile = jest.fn(fileName => {
+        if (fileName === '.npmrc') {
+          return 'save-exact = true\npackage-lock = false\n';
+        }
+        return null;
+      });
+      const res = await npmExtract.extractDependencies(
+        input01Content,
+        'package.json',
+        { global: {} }
+      );
+      expect(res.npmrc).toBeDefined();
+    });
     it('finds and discards .npmrc', async () => {
       platform.getFile = jest.fn(fileName => {
         if (fileName === '.npmrc') {