This. 
By having a option for pin-pointed tweaking of the Indian economy as desired,
by reducing the demand for physical gold whenever necessary,
by issuing a new tranche/series of SGBs.
This was also discussed recently in this topic-thread.
Such a scenario is an actual risk for typical debt (eg. corporate bonds).
For example, if long-term debt is refinanced periodically by short-term debt - Duration gap - Wikipedia
This is NOT an issue in case of sovereign debt (eg. GSECs, Tbills ,SGBs),
as RBI can always choose to “print money” and fulfill its debts.
By doing so, the impact on us will be in the form of devaluing the currency (INR) and NOT in the form of failure to receive the interest due or receive the principal upon maturity.