findSequenceOnDisk formats incorrect result with 2-frame sequence

[justinfx]

The C++ findSequenceOnDisk() function is returning the wrong result, given the following files on disk:

seq/foo.0001.ext
seq/foo.0002.ext

And either of these calls return the same result:

findSequenceOnDisk("seq/foo.0001.ext");
findSequenceOnDisk("seq/foo.#.ext"); 

Actual:

"seq/foo.12#.ext"

Expected:

"seq/foo.1,2#.ext"

If there are 3 files in the sequence, the bug does not occur.

This case has been tested as working under the equivalent Go library code.

[justinfx]

It turns out there was a bug in the underlying framesToFrameRange() function when it comes to handling a 2-frame range. There was some bad string formatting.
Fixed and released as v2.11.1