Longest terms of lady Prime Ministers?

Based on the following data, Sirimavo Bandaranaike of Sri Lanka should be credited as the longest serving female prime minister in the world. However, Indira Gandhi of India seems to be receiving this credit. Can somebody throw some light on this? (Does this have anything to do with the change in name of Ceylon to Sri Lanka?)

The following data is from Wikipedia:

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# Indira Gandhi, India –

In office:
24 January 1966 – 24 March 1977 &
14 January 1980 – 31 October 1984
(= 5829 days ~ almost 16 years)

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# Sirimavo Bandaranaike, Sri Lanka –

In office:
Ceylon: 21 July 1960 – 27 March 1965 & 29 May 1970 – 22 May 1972
Sri Lanka: 22 May 1972 – 23 July 1977 & 14 November 1994 – 10 August 2000
(= 6418 days ~ 17.5 years!?)

Thanks,