Skip running db migration on ghost install

- @todo: add tests
- @todo: what about `ghost setup migrate`?

[ci skip]

lib/commands/setup.js

@@ -41,6 +41,7 @@ class SetupCommand extends Command {
         const os = require('os');
         const url  = require('url');
         const path = require('path');
+        const semver = require('semver');
 
         const linux = require('../tasks/linux');
         const migrate = require('../tasks/migrate');
@@ -81,6 +82,7 @@ class SetupCommand extends Command {
                 });
 
                 // Special-case migrations
+                // @TODO: how to manage ghost setup migrate in 2.0?
                 if (argv.stages.includes('migrate')) {
                     tasks.push({title: 'Running database migrations', task: migrate})
                 }
@@ -171,10 +173,20 @@ class SetupCommand extends Command {
             }));
 
             if (argv.migrate !== false) {
+                const instance = this.system.getInstance();
+
                 // Tack on db migration task to the end
                 tasks.push({
                     title: 'Running database migrations',
-                    task: migrate
+                    task: migrate,
+                    // CASE: We are about to install Ghost 2.0. We moved the execution of knex-migrator into Ghost.
+                    enabled: () => {
+                        if (semver.satisfies(instance.cliConfig.get('active-version'), '^2.0.0')) {
+                            return false;
+                        }
+
+                        return true;
+                    }
                 });
             }