[solo.commands.command] simplify and improve bash completions

Note: <tab> below can mean double <tab>.

This commit fixes cases such like the following ones:

* crash (issue !73) - e.g. KeyError: u'--mtime':
    - equo security oscheck --mtime <tab>
    - equo query graph --complete <tab>
      (this was due to a typo in variable name)

* now prints options, previously it didn't:
    - equo install -a <tab>

* crashed, or (with only variable name fixed) didn't print all options:
    - equo security oscheck --mtime <tab>
      (note that it worked with more special -q instead of --mtime etc.)

* didn't print all options:
    - equo query list installed <tab>
      (now shows also --by-user)

The following behaviour is still buggy:

* last typed word (note: no space before <tab>) disappears upon completion:
    - equo security oscheck<tab>
      (not a regression)
    - equo install --deep<tab>
      (here it's an option; regression! - previously it didn't complete but
      didn't cause the word to be erased either)

These can be corrected reliably when something like ${COMP_WORDS[COMP_CWORD]}
(from complete -F) is passed to the Python side.
Without this it's not possible to distinguish between `recognized_option<tab>`
(completion of recognized_option) and `recognized_option <tab>`.

client/solo/commands/command.py

@@ -183,35 +183,23 @@ class SoloCommand(object):
         This method implements bash completion through
         a hierarchical (commands) dictionary object.
         """
-        # navigate through commands, finding the list of commands
         _commands = commands
 
-        if not self._args:
-            # show all the commands
-            outcome += sorted(commands.keys())
-
-        for index, item in enumerate(self._args):
-            if item in _commands:
-                _commands = commands[item]
-                if index == (len(self._args) - 1):
-                    # if this is the last one, generate
-                    # proper outcome elements.
-                    outcome += sorted(_commands.keys())
-                    # reset last_arg so that outcome list
-                    # won't be filtered
-                    last_arg = ""
-            elif index == (len(self._args) - 1):
-                # if this is the last one, and item
-                # is not in _commands, outcome becomes
-                # _commands.keys()
-                outcome += sorted(_commands.keys())
-                # no need to break here
-            else:
-                # item not in commands, but that's not the
-                # last one, we must generate proper outcome
-                # elements and stop right after
-                outcome += sorted(_commands.keys())
+        last_arg_recognised = False
+        for item in self._args:
+            if item not in _commands:
+                last_arg_recognised = False
                 break
+            last_arg_recognised = True
+            if item.startswith("-"):
+                continue
+            _commands = _commands[item]
+
+        outcome += sorted(_commands.keys())
+
+        if last_arg_recognised:
+            # Make it so all outcomes will be displayed, not filtered out.
+            last_arg = None
 
         return self._bashcomp(sys.stdout, last_arg, outcome)