substr of 1 char length at end of string generates code that gives IndexError

[snoopyjc]

substr of 1 char length at end of string generates code that gives IndexError. In perl a substr at the end of the string should give the empty string as the result, not an IndexError exception.

[snoopyjc]

Fixed in my v0.961 with an additional fix for ++/-- in substr in v0.966: https://github.com/snoopyjc/pythonizer/