From 8eb8d16c194afec720d90f98aec46d63d5bbb33a Mon Sep 17 00:00:00 2001
From: Raul Tambre <raul@tambre.ee>
Date: Fri, 24 Jun 2022 21:21:17 +0300
Subject: cmSystemTools: Fix unsetenv() fallback

The fallback path boils down to putenv(). Calling that with a "=" sets the
variable to an empty string.
Use cmSystemTools::UnPutEnv() instead, which correctly handles unsetting
variables on a variety of systems.
---
 Source/cmSystemTools.cxx | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 55b0df8..3de45bc 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -1501,8 +1501,7 @@ std::string cmSystemTools::RelativeIfUnder(std::string const& top,
 bool cmSystemTools::UnsetEnv(const char* value)
 {
 #  if !defined(HAVE_UNSETENV)
-  std::string var = cmStrCat(value, '=');
-  return cmSystemTools::PutEnv(var);
+  return cmSystemTools::UnPutEnv(value);
 #  else
   unsetenv(value);
   return true;
-- 
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