FR: Automatic retrying dirty migrations after fail

[lukashes]

If I have broken migration, I get the error:

error: migration failed in line 0:...

I fixed problem and start migrations again:

error: Dirty database version 169. Fix and force version.

For manual migrations no problems, because I can use force 168 command and start it again.

But for automatic deployment systems it is uncomfortable following to the dirty migrations. The simplest way to try migration again. What do you think about this feature as adding new option migrate up --ignore-dirty?