Fix handling of incorrect %z cqlshlib output on Windows

Patch by jmckenzie; reviewed by aweisberg for CASSANDRA-9418

bin/cqlsh.py

@@ -945,7 +945,7 @@ class Shell(cmd.Cmd):
             try:
                 import readline
             except ImportError:
-                if platform.system() == 'Windows':
+                if myplatform == 'Windows':
                     print "WARNING: pyreadline dependency missing.  Install to enable tab completion."
                 pass
             else:

pylib/cqlshlib/formatting.py

@@ -16,16 +16,20 @@
 
 import calendar
 import math
+import platform
 import re
 import sys
 import platform
 import time
 from collections import defaultdict
+
 from . import wcwidth
 from .displaying import colorme, FormattedValue, DEFAULT_VALUE_COLORS
 from datetime import datetime, timedelta
 from cassandra.cqltypes import EMPTY
 
+is_win = platform.system() == 'Windows'
+
 unicode_controlchars_re = re.compile(r'[\x00-\x31\x7f-\xa0]')
 controlchars_re = re.compile(r'[\x00-\x31\x7f-\xff]')
 
@@ -193,15 +197,24 @@ def strftime(time_format, seconds):
         offset = -time.altzone
     else:
         offset = -time.timezone
-    if formatted[-4:] != '0000' or time_format[-2:] != '%z' or offset == 0:
+    if not is_win and (formatted[-4:] != '0000' or time_format[-2:] != '%z' or offset == 0):
         return formatted
+    elif is_win and time_format[-2:] != '%z':
+        return formatted
+
     # deal with %z on platforms where it isn't supported. see CASSANDRA-4746.
     if offset < 0:
         sign = '-'
     else:
         sign = '+'
     hours, minutes = divmod(abs(offset) / 60, 60)
-    return formatted[:-5] + sign + '{0:0=2}{1:0=2}'.format(hours, minutes)
+    # Need to strip out invalid %z output on Windows. C libs give us 'Eastern Standard Time' instead of +/- GMT
+    if is_win and time_format[-2:] == '%z':
+        # Remove chars and strip trailing spaces left behind
+        formatted = re.sub('[A-Za-z]', '', formatted).rstrip()
+        return formatted + sign + '{0:0=2}{1:0=2}'.format(hours, minutes)
+    else:
+        return formatted[:-5] + sign + '{0:0=2}{1:0=2}'.format(hours, minutes)
 
 @formatter_for('Date')
 def format_value_date(val, colormap, **_):