BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=1985

Reconfig option should not only update build config files. This option
should reset environment value set by edksetup script, such as
EDK_TOOLS_PATH/PYTHONPATH. If so, this option will be valuable for
the user to switch the different WORKSPACEs.

We can locate BASETOOLS by setting the WORKSPACE in a directory
separate from BASETOOLS,but it can't switch workspaces.
for example, set WORKSPACE=C:\work\edk2 in directory C:\
run C:\work\edk2\edksetup in directory C:\
switch workspaces, set WORKSPACE=C:\workspace\edk2
run C:\workspace\edk2\edksetup in directory C:\
This situation does not apply with Reconfig,
So I use the "clean" option to clear the environment variables
associated with edksetup
run "C:\workspace\edk2\edksetup clean" in directory C:\,
run "C:\workspace\edk2\edksetup" in directory C:\

This patch is going to fix that issue.

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>
---
 edksetup.bat | 28 ++++++++++++++++++++++++++--
 edksetup.sh  | 31 ++++++++++++++++++++++++++++---
 2 files changed, 54 insertions(+), 5 deletions(-)

diff --git a/edksetup.bat b/edksetup.bat
index 024f57a4b7..00075ca48e 100755
--- a/edksetup.bat
+++ b/edksetup.bat
@@ -25,6 +25,29 @@
 pushd .
 cd %~dp0
 
+if /I "%1" neq "Reconfig" (
+  if /I "%1" neq "EnvClean" (
+    goto CheckCD
+  )
+)
+
+set EDK_TOOLS_BIN=
+set CONF_PATH=
+set BASETOOLS_PYTHON_SOURCE=
+set EDK_TOOLS_PATH=
+set WORKSPACE=
+
+if /I "%1"=="Reconfig" (
+  echo reset environment value set by edksetup script
+  goto CheckCD
+)
+
+if /I "%1"=="EnvClean" (
+  echo clean environment value set by edksetup script
+  goto end
+)
+
+:CheckCD
 if not defined WORKSPACE (
   goto SetWorkSpace
 )
@@ -142,9 +165,10 @@ if "%1"=="" goto end
 
 :Usage
   @echo.
-  @echo  Usage: "%0 [-h | -help | --help | /h | /help | /?] [Reconfig] [Rebuild] [ForceRebuild] [VS2019] [VS2017] [VS2015] [VS2013] [VS2012]"
+  @echo  Usage: "%0 [-h | -help | --help | /h | /help | /?] [Reconfig] [Rebuild] [EnvClean] [ForceRebuild] [VS2019] [VS2017] [VS2015] [VS2013] [VS2012]"
   @echo.
-  @echo         Reconfig       Reinstall target.txt, tools_def.txt and build_rule.txt.
+  @echo         Reconfig       Reinstall target.txt, tools_def.txt， build_rule.txt and reset environment value set by edksetup script.
+  @echo         EnvClean       Clean environment value by edksetup script.
   @echo         Rebuild        Perform incremental rebuild of BaseTools binaries.
   @echo         ForceRebuild   Force a full rebuild of BaseTools binaries.
   @echo         VS2012         Set the env for VS2012 build.
diff --git a/edksetup.sh b/edksetup.sh
index 06d2f041e6..211cdc7230 100755
--- a/edksetup.sh
+++ b/edksetup.sh
@@ -33,6 +33,8 @@ function HelpMsg()
   echo "  --reconfig            Overwrite the WORKSPACE/Conf/*.txt files with the"
   echo "                        template files from the BaseTools/Conf directory."
   echo
+  echo "  --envclean            Clean environment value by edksetup script."
+  echo
   echo Please note: This script must be \'sourced\' so the environment can be changed.
   echo ". $SCRIPTNAME"
   echo "source $SCRIPTNAME"
@@ -44,6 +46,20 @@ function SetWorkspace()
   # If WORKSPACE is already set, then we can return right now
   #
   export PYTHONHASHSEED=1
+  if [ -n $RECONFIG ]
+  then
+    echo reset environment value set by edksetup script
+    WORKSPACE=
+    CONF_PATH=
+  fi
+
+  if [ -n $ENVCLEAN ]
+  then
+    echo clean environment value by edksetup script
+    WORKSPACE=
+    CONF_PATH=
+    return 0
+  fi
   if [ -n "$WORKSPACE" ]
   then
     return 0
@@ -177,9 +193,14 @@ function SetupPython()
 
 function SourceEnv()
 {
-  SetWorkspace &&
-  SetupEnv
-  SetupPython
+  if [ -n $ENVCLEAN ]
+  then
+    SetWorkspace
+  else
+    SetWorkspace &&
+    SetupEnv &&
+    SetupPython
+  fi
 }
 
 I=$#
@@ -194,6 +215,10 @@ do
       RECONFIG=TRUE
       shift
     ;;
+    --envclean)
+    ENVCLEAN=TRUE
+    shift
+    ;; 
     *)
       HelpMsg
       break
-- 
2.14.1.windows.1