title: site/perl directory is missing in perl @INC search path
body: <p>I am developing a bunch of Perl scripts for my workmates and me.
  To ease distribution, Perl itself resides on a network path and is used from there directly using this header:</p>
  
  <pre><code>@rem = '--*-Perl-*--
  @echo off
  \\network\path\to\Perl\bin\perl.exe -x -S %0 %*
  goto EndOfPerl
  @rem ';
  #!perl
  #line 8
  #####################################################################
  </code></pre>
  
  <p>This worked fine (and still does!), but a collegue needed a standalone version, so we copied the complete network installation of Perl to the local hard disk.
  After changing the header to use the local location we get the message:</p>
  
  <pre><code>Can't locate Tk.pm in @INC (@INC contains: C:/tools/Perl/5.16.1/lib .) at Test.cmd line 30
  </code></pre>
  
  <p>Now I always thought @INC was compiled into Perl. At least, it shouldn't change by simply copying Perl to another location.</p>
  
  <p>There is a slight difference in Perl -V output when started locally.</p>
  
  <p>Here is what I get when started from the network:</p>
  
  <pre><code>Summary of my perl5 (revision 5 version 16 subversion 1) configuration:
    Platform:
      osname=MSWin32, osvers=5.2, archname=MSWin32-x86-multi-thread
      uname=''
      config_args='undef'
      hint=recommended, useposix=true, d_sigaction=undef
      useithreads=define, usemultiplicity=define
      useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
      use64bitint=undef, use64bitall=undef, uselongdouble=undef
      usemymalloc=n, bincompat5005=undef
    Compiler:
      cc='cl', ccflags ='-nologo -GF -W3 -MD -Zi -DNDEBUG -O1 -DWIN32 -D_CONSOLE -DNO_STRICT -DPERL_TEXTMODE_SCRIPTS -DUSE_SITECUSTOMIZE -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO -D_USE_32BIT_TIME_T',
      optimize='-MD -Zi -DNDEBUG -O1',
      cppflags='-DWIN32'
      ccversion='12.00.8168', gccversion='', gccosandvers=''
      intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
      d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=8
      ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='__int64',
      lseeksize=8
      alignbytes=8, prototype=define
    Linker and Libraries:
      ld='link', ldflags ='-nologo -nodefaultlib -debug -opt:ref,icf
      -libpath:"C:\Perl\lib\CORE"  -machine:x86'
      libpth=\lib
      libs=oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  netapi32.lib uuid.lib ws2_32.lib mpr.lib
      winmm.lib  version.lib odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
      perllibs=oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib  comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  netapi32.lib uuid.lib ws2_32.lib mpr.lib winmm.lib  version.lib odbc32.lib odbccp32.lib comctl32.lib msvcrt.lib
      libc=msvcrt.lib, so=dll, useshrplib=true, libperl=perl516.lib
      gnulibc_version=''
    Dynamic Linking:
      dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
      cccdlflags=' ', lddlflags='-dll -nologo -nodefaultlib -debug -opt:ref,icf  -libpath:"C:\Perl\lib\CORE"  -machine:x86'
  
  
  Characteristics of this binary (from libperl):
    Compile-time options: HAS_TIMES HAVE_INTERP_INTERN MULTIPLICITY
                          PERLIO_LAYERS PERL_DONT_CREATE_GVSV
                          PERL_IMPLICIT_CONTEXT PERL_IMPLICIT_SYS
                          PERL_MALLOC_WRAP PERL_PRESERVE_IVUV PL_OP_SLAB_ALLOC
                          USE_ITHREADS USE_LARGE_FILES USE_LOCALE
                          USE_LOCALE_COLLATE USE_LOCALE_CTYPE
                          USE_LOCALE_NUMERIC USE_PERLIO USE_PERL_ATOF
                          USE_SITECUSTOMIZE
    Locally applied patches:
          ActivePerl Build 1601 [296175]
    Built under MSWin32
    Compiled at Aug 30 2012 20:08:55
    @INC:
      //network/path/to/Perl/site/lib
      //network/path/to/Perl/Perl/lib
      .
  </code></pre>
  
  <p>And here is the output when executed from the local drive:</p>
  
  <pre><code>&lt;snip&gt;
  Compiled at Aug 30 2012 20:08:55
    %ENV:
      PERL_DIR="C:\tools\Perl\5.16.1"
    @INC:
      C:/tools/Perl/5.16.1/lib
      .
  </code></pre>
  
  <p>The site/lib part is gone!
  Any ideas, anyone?</p>