a git dependency defined as url cannot be updated-fails with a git conflict in my cache

[capaj]

I am on yarn 0.20.3

What is the current behavior?
I have a url in my deps: "trae": "https://github.com/capaj/trae.git",
I run yarn
I make a commit to https://github.com/capaj/trae.git repo.
I run yarn add https://github.com/capaj/trae.git to get the latest version from my repo
I get:

y add https://github.com/capaj/trae.git
yarn add v0.20.3
[1/4] Resolving packages...
error Command failed.
Exit code: 128
Command: git
Arguments: pull
Directory: /home/capaj/.cache/yarn/.tmp/a0218de46c09eeeba3aa6e9bed4d0f17
Output:
error: Pull is not possible because you have unmerged files.
hint: Fix them up in the work tree, and then use 'git add/rm <file>'
hint: as appropriate to mark resolution and make a commit.
fatal: Exiting because of an unresolved conflict.
info Visit https://yarnpkg.com/en/docs/cli/add for documentation about this command.

What is the expected behavior?
Expected is that it install the trae package from my github url fine without any git errors.

Ubuntu 16.10, Node 7.5.0

[bestander]

Yarn clones git dependencies into a cache folder.
I think it tries to reuse the same folder second time, that might be hard because Yarn may copy some files into cache during linking phase.
I suppose instead of updating it should create a new cache folder if HEAD changed.
PR is welcome

[tom10271]

What can I do if I face this problem?

[BYK]

What can I do if I face this problem?

I would try the latest nightly since this seems to be solved on master.

[remotealex]

Deleting the tmp dir fixes the issue too

Directory: /Users/alexprice/Library/Caches/Yarn/v1/.tmp/a71eb20c6f8366926c96610aa7b336f4
....

$ rm -rf ~/Library/Caches/Yarn/v1/.tmp/a71eb20c6f8366926c96610aa7b336f4

[joshuapinter]

You can fixed this by running yarn cache clean as well.