backup/restore: fix termstatus initialization

The termstatus must only be canceled once the command has returned.
Otherwise output may be lost when the context gets canceled.

cmd/restic/cmd_backup.go

@@ -54,7 +54,7 @@ Exit status is 3 if some source data could not be read (incomplete snapshot crea
 	},
 	DisableAutoGenTag: true,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		term, cancel := setupTermstatus(cmd.Context())
+		term, cancel := setupTermstatus()
 		defer cancel()
 		return runBackup(cmd.Context(), backupOptions, globalOptions, term, args)
 	},

cmd/restic/cmd_restore.go

@@ -37,7 +37,7 @@ Exit status is 0 if the command was successful, and non-zero if there was any er
 `,
 	DisableAutoGenTag: true,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		term, cancel := setupTermstatus(cmd.Context())
+		term, cancel := setupTermstatus()
 		defer cancel()
 		return runRestore(cmd.Context(), restoreOptions, globalOptions, term, args)
 	},

cmd/restic/termstatus.go

@@ -13,13 +13,14 @@ import (
 //
 // Expected usage:
 // ```
-// term, cancel := setupTermstatus(ctx)
+// term, cancel := setupTermstatus()
 // defer cancel()
 // // do stuff
 // ```
-func setupTermstatus(ctx context.Context) (*termstatus.Terminal, func()) {
+func setupTermstatus() (*termstatus.Terminal, func()) {
 	var wg sync.WaitGroup
-	cancelCtx, cancel := context.WithCancel(ctx)
+	// only shutdown once cancel is called to ensure that no output is lost
+	cancelCtx, cancel := context.WithCancel(context.Background())
 
 	term := termstatus.New(globalOptions.stdout, globalOptions.stderr, globalOptions.Quiet)
 	wg.Add(1)