Benchmark Groups Have Some Minor Problems

[ericsnowcurrently]

(See https://github.com/pyston/python-macrobenchmarks/pull/10.)

• [x] a benchmark group "all" is allowed, but ignored
• [x] duplicate groups are allowed (between manifest files) but the semantics aren't clear
• [ ] a group will overwrite a tag with the same name, without warning
• [x] the "list_groups" command does not show tags if any custom groups are defined
• [x] tags aren't found properly in BenchmarksManifest.resolve_group()

[ericsnowcurrently]

Also "list -b TAG" isn't working.

[ericsnowcurrently]

Also, if the "default" group includes a name that does not exist then it is ignored, whether or not "-NAME". I'd expect it to fail like it does for any other group.

[ericsnowcurrently]

@kmod, the main problem from https://github.com/pyston/python-macrobenchmarks/pull/10 is due to how a custom group named "all" is getting ignored. I'm probably going to just disallow such a group.