[patch][python] Consistently use $srcfile in py-breakpoint.exp

[Pedro Alves]

On 04/30/2018 01:04 PM, Phil Muldoon wrote:
> This patch replaces py-breakpoint.exp's inconsistent use of string
> literals for source file name checks and replaces all instances
> with checks against $srcfile.

Nit: I think there's one "replaces" too many above.  I think
something like this would be clearer:

 This patch fixes py-breakpoint.exp's inconsistent use of both
 string literals and $srcfile for source file name checks by
 using $srcfile throughout.

OK with that fixed.  Please push.

Thanks,
Pedro Alves