Merge #11175

11175: cli: Fix issue with pulumi new and unstaged files r=Frassle a=Frassle

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# Description

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Fixes #11121

## Checklist

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- [ ] I have added tests that prove my fix is effective or that my feature works
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- [ ] I have run `make changelog` and committed the `changelog/pending/<file>` documenting my change
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Co-authored-by: Justin Van Patten <jvp@justinvp.com>

changelog/pending/20221027--cli--hard-reset-the-templates-checkout-to-work-around-a-go-git-issue-with-ignored-files.yaml

@@ -0,0 +1,4 @@
+changes:
+- type: fix
+  scope: cli
+  description: Hard reset the templates checkout to work around a go-git issue with ignored files.

sdk/go/common/util/gitutil/git.go

@@ -324,6 +324,16 @@ func gitCloneOrPull(url string, referenceName plumbing.ReferenceName, path strin
 				return err
 			}
 
+			// There are cases where go-git gets confused about files that were included in .gitignore
+			// and then later removed from .gitignore and added to the repository, leaving unstaged
+			// changes in the working directory after a pull. To address this, we'll first do a hard
+			// reset of the worktree before pulling to ensure it's in a good state.
+			if err := w.Reset(&git.ResetOptions{
+				Mode: git.HardReset,
+			}); err != nil {
+				return err
+			}
+
 			if cloneErr = w.Pull(&git.PullOptions{
 				ReferenceName: referenceName,
 				SingleBranch:  true,