From cdd9e8df3723c315686f90eb08bc2876ebdb8601 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Tue, 6 Sep 2022 12:18:18 +0200
Subject: [PATCH] build_env(): respect the `MSYS` environment variable

With this commit, you can call

	MSYS=noemptyenvvalues my-command

and it does what is expected: to pass no empty-valued environment
variables to `my-command`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 winsup/cygwin/environ.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/environ.cc b/winsup/cygwin/environ.cc
index 69647a4101..97e75ce716 100644
--- a/winsup/cygwin/environ.cc
+++ b/winsup/cygwin/environ.cc
@@ -1204,7 +1204,11 @@ build_env (const char * const *envp, PWCHAR &envblock, int &envc,
     {
       bool calc_tl = !no_envblock;
 #ifdef __MSYS__
-      if (!keep_posix)
+      if (ascii_strncasematch(*srcp, "MSYS=", 5))
+        {
+          parse_options (*srcp + 5);
+	}
+      else if (!keep_posix)
         {
           /* Don't pass timezone environment to non-msys applications */
           if (ascii_strncasematch(*srcp, "TZ=", 3))