Check commit message hashes before making links

Previously, when formatting commit messages, anything
that looked like SHA1 hashes was turned into a link
using regex. This meant that certain phrases or numbers
such as `777777` or `deadbeef` could be recognized as a commit
even if the repository has no commit with those hashes.

This change will make it so that anything that looks
like a SHA1 hash using regex will then also be checked
to ensure that there is a commit in the repository
with that hash before making a link.

Signed-off-by: Gary Kim <gary@garykim.dev>

models/repo.go

@@ -508,8 +508,9 @@ func (repo *Repository) mustOwnerName(e Engine) string {
 func (repo *Repository) ComposeMetas() map[string]string {
 	if repo.ExternalMetas == nil {
 		repo.ExternalMetas = map[string]string{
-			"user": repo.MustOwner().Name,
-			"repo": repo.Name,
+			"user":     repo.MustOwner().Name,
+			"repo":     repo.Name,
+			"repoPath": repo.RepoPath(),
 		}
 		unit, err := repo.GetUnit(UnitTypeExternalTracker)
 		if err != nil {