@@ -31,6 +31,13 @@ function get_pip_command {

 # Get the path to the direcotry where python executables are installed.

 # get_python_exec_prefix

 function get_python_exec_prefix {

+    local xtrace=$(set +o | grep xtrace)

+    set +o xtrace

+    if [[ -z "$os_PACKAGE" ]]; then

+        GetOSVersion

+    fi

+    $xtrace

+

     if is_fedora || is_suse; then

         echo "/usr/bin"

     else

@@ -39,8 +46,8 @@ function get_python_exec_prefix {

 }

 # Wrapper for ``pip install`` to set cache and proxy environment variables

-# Uses globals ``INSTALL_TESTONLY_PACKAGES``, ``OFFLINE``, ``TRACK_DEPENDS``,

-# ``*_proxy``

+# Uses globals ``INSTALL_TESTONLY_PACKAGES``, ``OFFLINE``, ``PIP_VIRTUAL_ENV``,

+# ``TRACK_DEPENDS``, ``*_proxy``

 # pip_install package [package ...]

 function pip_install {

     local xtrace=$(set +o | grep xtrace)

@@ -62,8 +69,13 @@ function pip_install {

         local cmd_pip=$DEST/.venv/bin/pip

         local sudo_pip="env"

     else

-        local cmd_pip=$(get_pip_command)

-        local sudo_pip="sudo -H"

+        if [[ -n ${PIP_VIRTUAL_ENV:=} && -d ${PIP_VIRTUAL_ENV} ]]; then

+            local cmd_pip=$PIP_VIRTUAL_ENV/bin/pip

+            local sudo_pip="env"

+        else

+            local cmd_pip=$(get_pip_command)

+            local sudo_pip="sudo -H"

+        fi

     fi

     local pip_version=$(python -c "import pip; \

@@ -93,6 +105,7 @@ function pip_install {

                 -r $test_req

         fi

     fi

+    $xtrace

 }

 # get version of a package from global requirements file