commit 137374fd6538cf9dee0cb22907728d8fdecb5832
author Bram Moolenaar <Bram@vim.org> Sun May 13 15:59:50 2018 +0200
committer Bram Moolenaar <Bram@vim.org> Sun May 13 15:59:50 2018 +0200
tree 300180a61a2e24db7bd4a085f99c710988b4632b
parent 8b62e31003693fee4b288e7aea49170f032aeef3

patch 8.0.1832: cannot use :unlet for an environment variable

Problem:    Cannot use :unlet for an environment variable.
Solution:   Make it work.  Use unsetenv() if available. (Ken Takata,
            closes #2855)

src/misc1.c

diff --git a/src/misc1.c b/src/misc1.c
index 6c77f4b..1ab55f0 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -4479,6 +4479,17 @@
     return pend;
 }
 
+    void
+vim_unsetenv(char_u *var)
+{
+#ifdef HAVE_UNSETENV
+    unsetenv((char *)var);
+#else
+    mch_setenv((char *)var, "", 0);
+#endif
+}
+
+
 /*
  * Our portable version of setenv.
  */