Isolation problems when using Mercurial repositories on build plans

Summary

When using a Mercurial repository, commits from a branch X are shown in the default branch as merged commits when no merge is performed.

Steps to Reproduce

1. Create a plan using a Mercurial repository
2. Create branch X and commit some data
3. Checkout the default branch and commit some data
4. Run the plan build for the default branch

Expected Results

Only the commit done for the default branch is shown on build results

Actual Results

Both commits from X and default branches are shown.
The commits from X are shown with an icon ("M") indicating they were merged on default but this is not the case