Nested executables fix

[onemen]

Implementing 'Nested executables fix' as suggested by #1210

• Use cwd instead of package directory when linking bin scripts
• Update package-linker module to filter calls to linkBin function
  (prevents [0.17.0] Error chmod-ing .bin files on 'yarn install' #1823)
• Update global module to only link root packages to the global bin
  folder
• Added tests

[torifat]

@onemen I have re-ran you test. It's passing now 👍

This is quite a big PR. Might take some time to review.

[bestander]

@onemen, thanks for the effort to add all those tests! 👍
Could you rebase please?

[onemen]

@bestander,

I will do the rebase later this week.
I want to add test, to make sure that the bins files are actually usable.
That every module can find the bins of its dependency.

Where can i found simple example for this?

[bestander]

Great work on tests!
Just need to make sure that we deal with conflicts correctly

[bestander]

I think top level dependencies should have a priority over nested ones

[onemen]

I can fix the sort at the top of copyModules function, let me know if it ok with you.
After this sort, we populate binLinks with top level dependencies first.

    // sorted tree makes file creation and copying not to interfere with each other
+   // prioritize top level dependencies
    flatTree = flatTree.sort(function(dep1, dep2): number {
-     return dep1[0].localeCompare(dep2[0]);
+     const [len1, len2] = [dep1[0].split(path.sep).length, dep2[0].split(path.sep).length];
+     return len1 === len2 ? dep1[0].localeCompare(dep2[0]) : len1 - len2;
    });

[bestander]

If that works then sure.
I thought it would be easier though if you iterate over the top dependencies first to generate a set of bins and then go through deeper dependencies discarding bins that are already in the set.

[bestander]

this test needs to verify that bin dependencies were flattened properly.
Especially for a case of conflicting bins

[skevy]

@onemen any updates on finishing up this PR?

[onemen]

I hope to find the time later this month.

I need to re-base the code and create new branch, since my old branch was corrupted

[thomasruiz]

@onemen any update?

[bestander]

ping.
Would be great to get this in, otherwise let's close the PR.

[bestander]

I'll close this PR for now.
Feel free to send a new one.