Prefer scalar assignment to get caller's first return value

Multiple forms of syntax can be used to obtain a package name from
`caller`, which emits this as its first return value, and assign
that name to a lexical scalar.

The following each achieve the same result, but with varying efficiency:
* `sub callme { my $package = caller(2); ...}`
* `sub callme { my ($package) = caller(2); ...}`
* `sub callme { my $package = (caller(2))[0]; ...}`

In the first example, `pp_caller` determines only the package name
and pushes it to the stack. In the other two examples, the other 10 of
`caller`'s return values are calculated and pushed onto the stack,
before being discarded.

This commit changes non-CPAN-first instances of the latter two forms
in core to the first form.

Note: There is a special exception to the equivalence described above,
when caller is use in list context within the DB package. Such a
usage instance in regen/warnings.pl therefore remains unchanged.

1 files changed, 2 insertions, 2 deletions

diff --git a/dist/Env/lib/Env.pm b/dist/Env/lib/Env.pm
index eaf30f15a3..991afddc02 100644
--- a/dist/Env/lib/Env.pm
+++ b/dist/Env/lib/Env.pm
@@ -1,6 +1,6 @@
 package Env;
 
-our $VERSION = '1.05';
+our $VERSION = '1.06';
 
 =head1 NAME
 
@@ -75,7 +75,7 @@ Gregor N. Purdy E<lt>F<gregor@focusresearch.com>E<gt>
 =cut
 
 sub import {
-    my ($callpack) = caller(0);
+    my $callpack = caller(0);
     my $pack = shift;
     my @vars = grep /^[\$\@]?[A-Za-z_]\w*$/, (@_ ? @_ : keys(%ENV));
     return unless @vars;