Add Close() method to gogitRepository (#8901)

In investigating #7947 it has become clear that the storage component of go-git repositories needs closing.

This PR adds this Close function and adds the Close functions as necessary.

In TransferOwnership the ctx.Repo.GitRepo is closed if it is open to help prevent the risk of multiple open files.

Fixes #7947

modules/context/repo.go

@@ -454,9 +454,18 @@ func RepoAssignment() macaron.Handler {
 		}
 		ctx.Repo.GitRepo = gitRepo
 
+		// We opened it, we should close it
+		defer func() {
+			// If it's been set to nil then assume someone else has closed it.
+			if ctx.Repo.GitRepo != nil {
+				ctx.Repo.GitRepo.Close()
+			}
+		}()
+
 		// Stop at this point when the repo is empty.
 		if ctx.Repo.Repository.IsEmpty {
 			ctx.Data["BranchName"] = ctx.Repo.Repository.DefaultBranch
+			ctx.Next()
 			return
 		}
 
@@ -515,6 +524,7 @@ func RepoAssignment() macaron.Handler {
 			ctx.Data["GoDocDirectory"] = prefix + "{/dir}"
 			ctx.Data["GoDocFile"] = prefix + "{/dir}/{file}#L{line}"
 		}
+		ctx.Next()
 	}
 }
 
@@ -636,6 +646,13 @@ func RepoRefByType(refType RepoRefType) macaron.Handler {
 				ctx.ServerError("RepoRef Invalid repo "+repoPath, err)
 				return
 			}
+			// We opened it, we should close it
+			defer func() {
+				// If it's been set to nil then assume someone else has closed it.
+				if ctx.Repo.GitRepo != nil {
+					ctx.Repo.GitRepo.Close()
+				}
+			}()
 		}
 
 		// Get default branch.
@@ -724,6 +741,8 @@ func RepoRefByType(refType RepoRefType) macaron.Handler {
 			return
 		}
 		ctx.Data["CommitsCount"] = ctx.Repo.CommitsCount
+
+		ctx.Next()
 	}
 }