Make sure comparison view works correctly when a default VCS branch is not called "default"

[Kami]

I tried to get COMP_EXECUTABLE setting to work with the following values, but It didn't appear to work:

COMP_EXECUTABLES = [
    ('Python 2.7.17 - idle conf 1', 'L'),
    ('Python 3.5.9 - idle conf 1', 'L'),
    ('Python 2.7.17 - loaded conf 1', 'L'),
    ('Python 3.5.9 - loaded conf 2', 'L'),
]

After digging into the code, I noticed that the code hard codes the default branch value name to default.

This obviously won't work when a default branch is not called default. I assume this default value is a carry-over / legacy from Mercurial support (please correct me if I'm missing or misunderstanding something)...

---

In this pull request, I updated it to use default_branch value of the Project model.

I believe this is a correct change and I tested it with a project where value of default_branch is performance_tracking and it works correctly.

With this change, name in the left "Executables" select box menu will now also be correct and won't include ... in branch ... part when a default branch is used.

Here is an example with the same COMP_EXECUTABLES setting value and Project.default_branch being set to performance_tracking.

Before:

After:

TODO

• Tests

[Kami]

I've added a test case in 393d0cd.

[tobami]

👍 Looks like we'll have to do a release soon!

[Kami]

Pushed a fix for a build failure due to a bad merge conflict resolution I did through the Github WebUI.

[Kami]

@tobami Anything else I need to do here?

If not, I appreciate if you can merge it when you get a chance so I can work on tests for #283 (those PRs touch the same files so I will wait until this PR is merged to avoid conflicts).

Thanks.

[tobami]

@tobami Anything else I need to do here?

nope, it's a very necessary fix, thanks a lot. Merging...