Fix package name for nested packages, in 2.12

[dwijnand]

This was causing no class to be found (!!) because it would define the
package as "pp.q" instead of "p.q".

[szeiger]

Must have been caused by the refactoring to the 2.12 classpath handling. I've seen and fixed a similar case while testing those changes.

[lrytz]

Do you know what is the condition to trigger this bug? In my local test MiMa 0.1.14 works correctly, also with a class p.q.A (https://github.com/lrytz/mima-test/commits/master)

[dwijnand]

You need to be running the 2.12 code path of MiMa, so switch to sbt 1.0.0-RC2. Then MiMa will false negative:

sbt:c> mimaReportBinaryIssues
[info] Compiling 1 Scala source to /s/mima-test/target/scala-2.12/classes ...

[info] Done compiling.

[info] c: found 0 potential binary incompatibilities while checking against a.b:c_2.12:0.0.1

[info] Total time: 1 s, completed 21-Jul-2017 11:41:21

[lrytz]

Got it, thanks. Yes, it reproduces.