internal alkyne stability to strong alkali
According to A Textbook of Organic Chemistry by V. K. Ahluwalia and Madhuri Goyal


  1-Butyne may be isomerised to a more stable 2-butyne in presence of alcoholic potassium hydroxide and the reverse of this reaction may occur with sodamide


(see 17.2.1 of Best Synthetic Methods: Acetylenes, Allenes and Cumulenes for reaction conditions in the 2-alkyne to 1-alkyne direction, actually many relevant reactions are in this book)

So in the present of the strong base $\ce{NaNH2}$ the internal alkyne $\ce{H3CC#CCH3}$ rearranges to $\ce{HC#CCH2CH3}$

My thinking is that with just hydroxide the more stable 2-butyne is favored, while if an even-stronger base is used, that fact that the acetylenic-H can deprotonate pulls the equilibrium toward 1-butyne. 

Additionally, see 17.2.11 Isomerisation of 1,4 bis(alkoxy)-2-butynes to the corresponding allenes, which is catalyzed by t-BuOK.

Add see table 17.1 "Base catalyzed isomerisations of acetylenic compounds" about 10 different internal acetylene reactions are listed in the table.