In 0804e97 we updated `github.com/go-sql-driver/mysql` to a pinned
commit (b4242bab7dc5) newer than the latest tagged release (v1.4.1) to
avoid needing to pull in an extra dep. that was removed since v1.4.1.
Unfortunately for reasons that are not perfectly clear updating
`github.com/google/certificate-transparency-go` is preferring v1.4.1
over the pseudo-version made from the commit newer than v1.4.1 that we
previously pinned.
Since there is movement on making a v1.5.0 go-sql-driver mysql release
tag and we can likely get ct-go to use that we'll temporarily accept
this downgrade to update ct-go.
Unit tests are confirmed to pass:
```
~/go/src/github.com/go-sql-driver/mysql$ git log --pretty=format:'%h' -n 1
72cd26f
~/go/src/github.com/go-sql-driver/mysql$ go test ./...
ok github.com/go-sql-driver/mysql 0.081s
```
The most recent tagged release of mysql is v1.4.1, from a year ago. It
also happens to pull in an unwanted dependency (appengine) that the
latest commit does not.
Tests pass:
$ go test -count=1 github.com/go-sql-driver/mysql
ok github.com/go-sql-driver/mysql 0.068s
Fixes#4530
Jacob Hoffman-Andrews
Daniel McCarney