use system mercurial
Issue #20368: Add tests for Tkinter methods exprstring(), exprdouble(),
exprlong() and exprboolean().
Merge heads
Issue #20368: The null character now correctly passed from Tcl to Python (in
unicode strings only).  Improved error handling in variables-related commands.
Issue #19761: Fixed Tkinter tests on OS X.
Issue #20426: When passing the re.DEBUG flag, re.compile() displays the debug output every time it is called, regardless of the compilation cache.
Skip expr* tests for large integers for Tcl <8.5.
The '**' operator is available only since 8.5 and in any case such large
integers are not supported on Tcl <8.5.