rename does not overwrite existing file on JVM

gistfile1.txt

$ > Foo.pm6; ./perl6-j -I. -e 'use Foo; say "alive"'
alive

$ > Foo.pm6; ./perl6-j -I. -e 'use Foo; say "alive"'
===SORRY!===
Failed to rename '/usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86.tmp' to '/usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86': File /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86 already exists

$ > Foo.pm6; RAKUDO_MODULE_DEBUG=1 ./perl6-j -I. -e 'use Foo'
     87032 RMD: Loading settings CORE
     87032 RMD: Setting up default paths: . blib
     87032 RMD: going to load Perl6::BOOTSTRAP
     87032 RMD: Settings CORE loaded
 269 87032 RMD: Attempting 'Foo' as a pragma
  69 87032 RMD:   'Foo' is not a valid pragma
  26 87032 RMD: Attempting to load 'Foo'
   8 87032 RMD:   Late loading 'Foo'
  20 87032 RMD: Parsing specs: .
  55 87032 RMD: Parsing specs:
    17 87032 RMD: Parsing specs: .
  16 87032 RMD: Parsing specs: blib
  30 87032 RMD: Parsing specs: /usr/home/christian/bin/rakudo.jvm/share/nqp/lib
 588 87032 RMD: try-load 7795C5BD3D21241ED31BB5DB19106B21CC622A86: /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/Foo.pm6
  55 87032 RMD: Trying to load 7795C5BD3D21241ED31BB5DB19106B21CC622A86 from /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp
  57 87032 RMD: Outdated precompiled /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86
                mtime: Instant:1468265673
                since: Instant:1468265719
 147 87032 RMD: Precompiling /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/Foo.pm6 into /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86.bc
     87079 RMD: Loading settings CORE
     87079 RMD: Setting up default paths: . blib
     87079 RMD: going to load Perl6::BOOTSTRAP
     87079 RMD: Settings CORE loaded
3974 87032 RMD: Precompiled /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/Foo.pm6 into /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86.bc
   9 87032 RMD: Writing dependencies and byte code to /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86.tmp
===SORRY!===
Failed to rename '/usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86.tmp' to '/usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86': File /usr/home/christian/perl6/perl6-roast-data/rakudo.jvm/.precomp/54B30A4BDF363852FC8D6905165A5E0131320458.1.468265383996E9/77/7795C5BD3D21241ED31BB5DB19106B21CC622A86 already exists

Proposed fix: Raku/nqp#296

To illustrate the problem with nqp-j:

$ touch foo bar
$ ./nqp-j -e 'nqp::rename("foo", "bar")'
File bar already exists
  in <mainline> (-e:1)
  in eval (gen/jvm/stage2/NQPHLL.nqp:1198)
  in  (gen/jvm/stage2/NQPHLL.nqp:1288)
  in command_eval (gen/jvm/stage2/NQPHLL.nqp:1285)
  in command_line (gen/jvm/stage2/NQPHLL.nqp:1269)
  in MAIN (gen/jvm/stage2/NQP.nqp:4143)
  in <mainline> (gen/jvm/stage2/NQP.nqp:4139)
  in  (gen/jvm/stage2/NQP.nqp)