fail "merging/merging" scripted test in travis-ci since December 2018

[xuwei-k]

🤔

https://travis-ci.org/sbt/sbt-assembly/jobs/478647768#L882

[info] [error] java.lang.Exception: file /tmp/sbt_419bffc2/a had wrong content:
[info] [error] 2
[info] [error] 1
[info] [error] 3
[info] [error] 1
[info] [error] *** instead of ***
[info] [error] 1
[info] [error] 2
[info] [error] 1
[info] [error] 3
[info] [error] 	at $94426f8c8ad71399f0ed$.mustContain(build.sbt:48)
[info] [error] 	at $94426f8c8ad71399f0ed$.$anonfun$testmerge$7(build.sbt:21)
[info] [error] 	at $94426f8c8ad71399f0ed$.$anonfun$testmerge$7$adapted(build.sbt:19)
[info] [error] 	at sbt.io.IO$.withTemporaryDirectory(IO.scala:475)

https://travis-ci.org/sbt/sbt-assembly/builds

https://github.com/sbt/sbt-assembly/commits/master

[xuwei-k]

Some MergeStrategy does not treat order of Seq[File]. I think order depends on classpath order. (maybe classpath order depends on sbt internal implementations 🤔)

Should we sort classpath in here?

• xuwei-k@c57b6c1
• https://travis-ci.org/xuwei-k/sbt-assembly/builds/478676090

[eed3si9n]

I guess it makes sense to sort.