I modified your code slightly to incorporate in my program.

sub expand_bash_var {
  my ($varhash, $dephash, $queue) = @_;

  $queue ||= [ keys %$varhash ];

  # for each item in the queue
  for (@$queue) {

    # make sure its dependencies are expanded
    expand_bash_var($varhash, $dephash, $dephash->{$_});

    # then interpolate the variables in this item
    $varhash->{$_} =~ s/\$\{?(\w+)\}?/$varhash->{$1}/g;
  }
}

sub get_depend {
  my $ebuildfname = shift;
  my $ebuildcontents;
  my %ebuildvars;
  my $pkgname = $ebuildfname;
  my %vardepend;

#  print "Getting depend for '$ebuildfname'\n";
  $pkgname =~ s|/usr/portage/||;
  $pkgname =~ s|(.+)/.+/(.+).ebuild|$1/$2|;
  my $pkg = parse_package_name($pkgname);
  $pkg->{version} =~ s/^-//;
  $ebuildvars{PV} = "$pkg->{version}$pkg->{suffix}";

  open EBUILD, "< $ebuildfname" or die "Couldn't open '$ebuildfname' t
+o get DEPEND\n";
  while(<EBUILD>) {
    $ebuildcontents .= $_;
  }
  close EBUILD;

  while($ebuildcontents =~ /\b([-A-Z0-9_]+)\s*=\s*\"(.*?)\"/sgc) {
    $ebuildvars{$1} = $2;
  }
  print "Calling expand_bash_var() for '$ebuildfname'\n";
  expand_bash_var(\%ebuildvars, \%vardepend);
  print "Done with expand_bash_var() for '$ebuildfname'\n";

  my $depend = $ebuildvars{'DEPEND'} || '';
  $depend .= " $ebuildvars{'RDEPEND'}" if(defined $ebuildvars{'RDEPEND
+'});
  $depend =~ s/(\s+|\n+)/ /gs;
  print "$depend\n";

  return $depend;
}
[download]

which gives me the output:

Deep recursion on subroutine "main::expand_bash_var" at ./portage.pl line 124.

The file it is processing contains:

RESTRICT="nostrip"
IUSE="3dfx sse mmx 3dnow xml2 truetype nls cjk doc ipv6 debug static p
+am sdk bindist"

filter-flags "-funroll-loops"

ALLOWED_FLAGS="-fstack-protector -march -mcpu -O -O1 -O2 -O3 -pipe"
strip-flags

if [ "${ARCH}" = "x86" ]
then
    if [ -z "${SYNAPTICS}" ]
    then
        SYNAPTICS="yes"
    fi
else
    unset SYNAPTICS
fi

USE_SNAPSHOT="no"

PATCH_VER="2.1.25.4"
FT2_VER="2.1.3"
XCUR_VER="0.3.1"
SISDRV_VER="311003-1"
SAVDRV_VER="1.1.27t"
MGADRV_VER="1_3_0beta"
VIADRV_VER="0.1"
SYNDRV_VER="0.12.0"

BASE_PV="${PV}"
MY_SV="${BASE_PV//\.}"
S="${WORKDIR}/xc"
SYNDIR="${WORKDIR}/synaptics"
SRC_PATH="mirror://xfree/${BASE_PV}/source"
HOMEPAGE="http://www.xfree.org"

X_PATCHES="http://dev.gentoo.org/~spyderous/xfree/patchsets/${PV}/XFre
+e86-${PV}-patches-${PATCH_VER}.tar.bz2
    http://www.cpbotha.net/files/dri_resume/xfree86-dri-resume-v8.patc
+h"

X_DRIVERS="http://people.mandrakesoft.com/~flepied/projects/wacom/xf86
+Wacom.c.gz
    http://www.probo.com/timr/savage-${SAVDRV_VER}.zip
    http://www.winischhofer.net/sis/sis_drv_src_${SISDRV_VER}.tar.gz
    http://w1.894.telia.com/~u89404340/touchpad/files/synaptics-${SYND
+RV_VER}.tar.bz2"
MS_COREFONTS="./andale32.exe ./arial32.exe
    ./arialb32.exe ./comic32.exe
    ./courie32.exe ./georgi32.exe
    ./impact32.exe ./times32.exe
    ./trebuc32.exe ./verdan32.exe
    ./webdin32.exe"
MS_FONT_URLS="${MS_COREFONTS//\.\//mirror://sourceforge/corefonts/}"

SRC_URI="${SRC_PATH}/X${MY_SV}src-1.tgz
    ${SRC_PATH}/X${MY_SV}src-2.tgz
    ${SRC_PATH}/X${MY_SV}src-3.tgz
    ${SRC_PATH}/X${MY_SV}src-4.tgz
    ${SRC_PATH}/X${MY_SV}src-5.tgz
    doc? ( ${SRC_PATH}/X${MY_SV}src-6.tgz
        ${SRC_PATH}/X${MY_SV}src-7.tgz )"

SRC_URI="${SRC_URI}
    ${X_PATCHES}
    ${X_DRIVERS}
    nls? ( mirror://gentoo/gemini-koi8-u.tar.bz2 )
    mirror://gentoo/eurofonts-X11.tar.bz2
    mirror://gentoo/xfsft-encodings.tar.bz2
    mirror://gentoo/XFree86-compose.dir-0.1.bz2
    mirror://gentoo/XFree86-en_US.UTF-8.old.bz2
    mirror://gentoo/XFree86-locale.alias.bz2
    mirror://gentoo/XFree86-locale.dir.bz2
    mirror://gentoo/gentoo-cursors-tad-${XCUR_VER}.tar.bz2
    truetype? ( !bindist? ( ${MS_FONT_URLS} ) )"

LICENSE="Adobe-X CID DEC DEC-2 IBM-X NVIDIA-X NetBSD SGI UCB-LBL XC-2
    bigelow-holmes-urw-gmbh-luxi christopher-g-demetriou national-semi
+conductor
    nokia tektronix the-open-group todd-c-miller x-truetype xfree86-1.
+0
    MIT SGI-B BSD FTL | GPL-2 MSttfEULA"
SLOT="0"
KEYWORDS="x86 ppc sparc alpha mips hppa amd64 ia64"

DEPEND=">=sys-apps/baselayout-1.8.3
    >=sys-apps/portage-2.0.50_pre9
    >=sys-libs/ncurses-5.1
    >=sys-libs/zlib-1.1.3-r2
    >=sys-devel/flex-2.5.4a-r5
    >=dev-libs/expat-1.95.3
    >=media-libs/freetype-${FT2_VER}-r2
    >=media-libs/fontconfig-2.1-r1
    >=x11-base/opengl-update-1.4
    >=x11-misc/ttmkfdir-3.0.4
    >=sys-apps/sed-4
    >=sys-devel/patch-2.5.9
    sys-apps/util-linux
    dev-lang/perl
    media-libs/libpng
    app-arch/unzip
    pam? ( >=sys-libs/pam-0.75 )
    truetype? ( !bindist? ( app-arch/cabextract ) )
    !virtual/x11
    !x11-libs/xft"

PDEPEND="x86? ( 3dfx? ( >=media-libs/glide-v3-3.10 ) )"

PROVIDE="virtual/x11
    virtual/opengl
    virtual/glu
    virtual/xft"

DESCRIPTION="XFree86: free X server"

PATCH_DIR=${WORKDIR}/patch
[download]