db_init doesn't work with --blank-with-db option

[JunjieW]

Description

vv/vv

Line 998 in 0534931

echo " $db_init"

Since using --blank-with-db option, wp-cli actually won't work since the working directory is not a WordPress installation.

Solution:

Use mysql command to execute .sql file, as long as the .sql file is a mysqldump.

I will create a pull request later for this issue.