gdal_calc amin fails when passing more than 23 input files
The issue you were running into was that the X variable from the calc input was colliding with the variable created by a loop in the doit function:
for X in range(0,nXBlocks):It appears this has already been fixed by the gdal developers (in not yet released code). It now evals the calc input in a private namespace (a dictionary), rather than in the function's local namespace, so the X variable from the loop doesn't conflict with the X value from the input any more.