There is an issue with version 1.9.5 release where using the changeset modifyColumn throws migration error stating jar in the classpath is missing. As recommended in the user dashboard for this known error, I added the modify-column.jar file along with the main liquibase-1.9.5.jar in the ant build file and also updated its properties file for this new jar. This addition of patch to the main API does not work.
Convinced by the 92% agility of the version 2.0, I replaced liquibase-1.9.5.jar and the modify-column.jar with liquibase-2.0.jar and upon re-running the changeset of modifyColumn still reports the same error.
I got this working by adding modify-column-2.0.jar in the classpath of the liquibase-2.0.jar