This reverts commit 8b586fe8.

This avoids an error when the previous version was a source checkout where both the directory and executable were called drush.

This reverts commit 19b9bfe4.

This reverts commit 0a770bb0.

This reverts commit b41f4424.

This reverts commit bdb4bb64.

This reverts commit 83e9bb1b.

This reverts commit 6e893e8a.

This reverts commit 1c123cae.

This reverts commit 5e402271.

This reverts commit 24ecfd44.

This reverts commit 2a6d5a61.