Handle old versions of /usr/bin/env when loading shell env (#10202)

This fixes #9786 by using an invocation of `/usr/bin/env` that's
supported by macOS 12.

As it turns out, on macOS 12 (and maybe 13?) `/usr/bin/env` doesn't
support the `-0` flag. In our case it would silently fail, since we
`exit 0` in our shell invocation and because the program we run and
whose exit code we check is the `$SHELL` and not `/usr/bin/env`.

What this change does is to drop the `-0` and instead split the
environment on `\n`. This works even if an environment variable contains
a newline character because that would then be escaped.

Release Notes:

- Fixed Zed not picking up shell environments correctly when running on
macOS 12. ([#9786](https://github.com/zed-industries/zed/issues/9786)).

Co-authored-by: Dave Smith <davesmithsemail@gmail.com>

crates/zed/src/main.rs

@@ -906,7 +906,7 @@ async fn load_login_shell_environment() -> Result<()> {
     // We still don't know why `$SHELL -l -i -c '/usr/bin/env -0'`  would
     // do that, but it does, and `exit 0` helps.
     let shell_cmd = format!(
-        "{}printf '%s' {marker}; /usr/bin/env -0; exit 0;",
+        "{}printf '%s' {marker}; /usr/bin/env; exit 0;",
         shell_cmd_prefix.as_deref().unwrap_or("")
     );
 
@@ -923,7 +923,7 @@ async fn load_login_shell_environment() -> Result<()> {
 
     if let Some(env_output_start) = stdout.find(marker) {
         let env_output = &stdout[env_output_start + marker.len()..];
-        for line in env_output.split_terminator('\0') {
+        for line in env_output.split_terminator('\n') {
             if let Some(separator_index) = line.find('=') {
                 let key = &line[..separator_index];
                 let value = &line[separator_index + 1..];