Revert "Support multiple VS installations"

This reverts commit 36d41cef.

Reason for revert: Script references VS_VERSION variable that was
renamed in the prior change, so it doesn't work.

Original change's description:
> Support multiple VS installations
>
> Currently, package_from_installed.py assumes only one version of VS is
> installed. It takes the path of the first installation.
>
> This could be incorrect in several ways:
> - Maybe both 2017 and 2019 (the supported versions) are installed and
>   although the user specified using 2019, the 2017 path comes first.
> - Maybe 2019 and 2022 are installed, and the 2022 path is used even
>   though it isn't supported.
>
> This CL fixes that issue by parsing the vswhere.exe output to confirm
> the VS version matches what the user specified, using its corresponding
> path.
>
> Change-Id: I2029a4f7126d0a45b5370ad58ab257df55571b3b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3458722
> Reviewed-by: Gavin Mak <gavinmak@google.com>
> Reviewed-by: Chris Blume <cblume@chromium.org>
> Commit-Queue: Chris Blume <cblume@chromium.org>
> Auto-Submit: Chris Blume <cblume@chromium.org>

Change-Id: I3d9147a7786f7f54f861087d16967b75d4afe2c5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3504193
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>

win_toolchain/package_from_installed.py

@@ -52,7 +52,6 @@ _vs_version = None
 _win_version = None
 _vc_tools = None
 SUPPORTED_VS_VERSIONS = ['2017', '2019']
-_allow_multiple_vs_installs = False
 
 
 def GetVSPath():
@@ -61,34 +60,12 @@ def GetVSPath():
   # version is installed.
   command = (r'C:\Program Files (x86)\Microsoft Visual Studio\Installer'
              r'\vswhere.exe -prerelease')
-  vs_version_marker = 'catalog_productLineVersion: '
-  vs_path_marker = 'installationPath: '
+  marker = 'installationPath: '
   output = subprocess.check_output(command, universal_newlines=True)
-  vs_path = None
-  vs_installs_count = 0
-  matching_vs_path = None
   for line in output.splitlines():
-    if line.startswith(vs_path_marker):
-      # The path information comes first
-      vs_path = line[len(vs_path_marker):]
-      vs_installs_count += 1
-    if line.startswith(vs_version_marker):
-      # The version for that path comes later
-      if line[len(vs_version_marker):] == VS_VERSION:
-        matching_vs_path = vs_path
-
-  if vs_installs_count == 0:
-    raise Exception('VS %s path not found in vswhere output' % (VS_VERSION))
-  if vs_installs_count > 1:
-    if not _allow_multiple_vs_installs:
-      raise Exception('Multiple VS installs detected. This is unsupported. '
-                      'It is recommended that packaging be done on a clean VM '
-                      'with just one version installed. To proceed anyway add '
-                      'the --allow_multiple_vs_installs flag to this script')
-    else:
-      print('Multiple VS installs were detected. This is unsupported. '
-            'Proceeding anyway')
-  return matching_vs_path
+    if line.startswith(marker):
+      return line[len(marker):]
+  raise Exception('VS %s path not found in vswhere output' % (_vs_version))
 
 
 def ExpandWildcards(root, sub_dir):
@@ -500,9 +477,6 @@ def main():
   parser.add_option('--repackage', action='store', type='string',
                     dest='repackage_dir', default=None,
                     help='Specify raw directory to be packaged, for hot fixes.')
-  parser.add_option('--allow_multiple_vs_installs', action='store_true',
-                    default=False, dest='allow_multiple_vs_installs',
-                    help='Specify if multiple VS installs are allowed.')
   (options, args) = parser.parse_args()
 
   if options.repackage_dir:
@@ -525,8 +499,6 @@ def main():
     global _win_version
     _win_version = options.winver
     global _vc_tools
-    global _allow_multiple_vs_installs
-    _allow_multiple_vs_installs = options.allow_multiple_vs_installs
     vs_path = GetVSPath()
     temp_tools_path = ExpandWildcards(vs_path, 'VC/Tools/MSVC/14.*.*')
     # Strip off the leading vs_path characters and switch back to / separators.