flyway -dryRunOutput causes a migrate when a colon is used instead of =

[dvdtknsn]

What version of Flyway are you using?

5.01

Which client are you using? (Command-line, Java API, Maven plugin, Gradle plugin, SBT plugin, ANT tasks)

Command line

What database are you using (type & version)?

Oracle XE 11gR2

What operating system are you using?

Win10

What did you do?

(Please include the content causing the issue, any relevant configuration settings, and the command you ran)
I ran: flyway -dryRunOutput:previewDeployment.sql migrate
Note that I used a colon : instead of =
But instead of failing, this goes ahead and performs a flyway migrate, which is precisely what I don't want because I want to generate the script as a precaution.

I know it's partly user error, but I would have expected this incorrect syntax to make the command fail.