Removed unnecessary try/except in do_shell

Since in the subprocess.Popen() call, shell=True and stderr=sys.stderr, errors get printed on stderr.  There is no need to catch an exception.

Author: tleonhardt

CHANGES.md

@@ -22,6 +22,7 @@ News
     * ``load`` command has better error checking and reporting
     * Clipboard copy and paste functionality is now handled by the **pyperclip** module
         * NOTE: This adds an additional required 3rd-party dependency
+    * ``shell`` command now supports redirection and piping of output
     * Added a lot of unit tests
 
 0.7.3

cmd2.py

@@ -479,9 +479,7 @@ def __init__(self, completekey='tab', stdin=None, stdout=None, use_ipython=False
         self.initial_stdout = sys.stdout
         self.history = History()
         self.pystate = {}
-        # noinspection PyUnresolvedReferences
-        self.keywords = self.reserved_words + [fname[3:] for fname in dir(self)
-                                               if fname.startswith('do_')]
+        self.keywords = self.reserved_words + [fname[3:] for fname in dir(self) if fname.startswith('do_')]
         self.parser_manager = ParserManager(redirector=self.redirector, terminators=self.terminators,
                                             multilineCommands=self.multilineCommands,
                                             legalChars=self.legalChars, commentGrammars=self.commentGrammars,
@@ -1142,11 +1140,8 @@ def do_shell(self, command):
         """Execute a command as if at the OS prompt.
 
     Usage:  shell <command> [arguments]"""
-        try:
-            proc = subprocess.Popen(command, stdout=self.stdout, stderr=sys.stderr, shell=True)
-            proc.communicate()
-        except FileNotFoundError as e:
-            self.perror(e.strerror, traceback_war=False)
+        proc = subprocess.Popen(command, stdout=self.stdout, stderr=sys.stderr, shell=True)
+        proc.communicate()
 
     def path_complete(self, text, line, begidx, endidx, dir_exe_only=False, dir_only=False):
         """Method called to complete an input line by local file system path completion.