V-next builds with a git tag can fail as it does not fetch new tags(annotated)

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Deepak Kumar Mishra, Support Engineer, EMEA TFS Team, brings this knowledge experience while working with one of his customers and this important piece of information might help a lot of users who are using Git repos in tfs and build tags using TFS 2015 V-next builds.

Issue Description:
We create a tag using a following command for a git repo in TFS
Git tag -a testtag -m “message”

After this we push it to TFS server which triggers a vnext build with the tag as a part of continuous integration and then we get the following error:
Git push origin --tags

2016-09-15T07:44:15.3207410Z Starting fetch...

2016-09-15T07:44:16.2188308Z Checking out 53e2403076d27fd1476d1e4bffd453e3db146039 to C:\Agent1\_work\6\s

2016-09-15T07:44:16.2328322Z ##[error]No valid git object identified by '53e2403076d27fd1476d1e4bffd453e3db146039' exists in the repository.

2016-09-15T07:44:16.3678457Z ##[error]Prepare repository failed with exception.

The following are the screenshots of the build failure.

b1 b2

After this when we do a clone the v-next build succeeds.

Cause:
Libgit2sharp used to have problem while fetch annotated tags .This is a TFS bug with annotated tags which has been fixed in TFS 2016

Resolution:
1. We found that this is a bug in TFS 2015 and has been fixed in TFS 2016.
2. The workaround as of now is to use light-weight tags instead of annotated tags which solved the issue. Details of the light weight tags are available at https://git-scm.com/book/en/v2/Git-Basics-Tagging
3. The fix has been tested and it works well in TFS 2016.

Written by: Deepak Kumar Mishra

Reviewed by: Nitish Nagpal, Support Escalation Engineer