capturing redirection fix

CHANGELOG.rst

@@ -47,6 +47,8 @@ None
 * Fixed issue with job management if a TTY existed but was not controlled
   by the process, posix only.
 * Jupyter kernel no longer times out when using foreign shells on startup.
+* Capturing redirections, e.g. ``$(echo hello > f.txt)``, no longer fails
+  with a decoding error.
 
 **Security:**
 

xonsh/built_ins.py

@@ -625,7 +625,7 @@ def run_subproc(cmds, captured=True):
     hist.last_cmd_rtn = prev_proc.returncode
     if write_target is None:
         # get output
-        output = ''
+        output = b''
         if prev_proc.stdout not in (None, sys.stdout):
             output = prev_proc.stdout.read()
         if captured: