fuzz: report error if Python code raised exception
I think that's what we wanted to do, given the most of the code block is
surrounded by try-except. 'lazymanifest(mdata)' is moved to the try block
as it can fail.
https://bz.mercurial-scm.org/1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..