BUG: when parsing partial date, use sane defaults for missing fields GH2618

dateutil uses the current date to fill in missing fields, this
is desirable for year and month, but will cause an exception
when code is run on the 31st day of a month, and trying to parse
"2000 2" as feb 2000, because feb doesn't have 31 days.

So we default to current year and month, but always the first of the month.

Author: y-p

RELEASE.rst

@@ -103,6 +103,7 @@ pandas 0.10.1
   - Upconvert datetime + datetime64 values when concatenating frames (GH2624_)
   - Raise a more helpful error message in merge operations when one DataFrame
     has duplicate columns (GH2649_)
+  - Fix partial date parsing issue occuring only when code is run at EOM  (GH2618_)
 
 **API Changes**
 
@@ -140,6 +141,7 @@ pandas 0.10.1
 .. _GH2700: https://github.com/pydata/pandas/issues/2700
 .. _GH2694: https://github.com/pydata/pandas/issues/2694
 .. _GH2686: https://github.com/pydata/pandas/issues/2686
+.. _GH2618: https://github.com/pydata/pandas/issues/2618
 
 pandas 0.10.0
 =============

pandas/src/inference.pyx

@@ -513,20 +513,24 @@ def convert_sql_column(x):
     return maybe_convert_objects(x, try_float=1)
 
 def try_parse_dates(ndarray[object] values, parser=None,
-                    dayfirst=False):
+                    dayfirst=False,default=None):
     cdef:
         Py_ssize_t i, n
         ndarray[object] result
 
-    from datetime import datetime
+    from datetime import datetime, timedelta
 
     n = len(values)
     result = np.empty(n, dtype='O')
 
     if parser is None:
+        if default is None: # GH2618
+           date=datetime.now()
+           default=datetime(date.year,date.month,1)
+
         try:
             from dateutil.parser import parse
-            parse_date = lambda x: parse(x, dayfirst=dayfirst)
+            parse_date = lambda x: parse(x, dayfirst=dayfirst,default=default)
         except ImportError: # pragma: no cover
             def parse_date(s):
                 try:
@@ -560,22 +564,26 @@ def try_parse_dates(ndarray[object] values, parser=None,
 
 def try_parse_date_and_time(ndarray[object] dates, ndarray[object] times,
                             date_parser=None, time_parser=None,
-                            dayfirst=False):
+                            dayfirst=False,default=None):
     cdef:
         Py_ssize_t i, n
         ndarray[object] result
 
-    from datetime import date, time, datetime
+    from datetime import date, time, datetime, timedelta
 
     n = len(dates)
     if len(times) != n:
         raise ValueError('Length of dates and times must be equal')
     result = np.empty(n, dtype='O')
 
     if date_parser is None:
+        if default is None: # GH2618
+           date=datetime.now()
+           default=datetime(date.year,date.month,1)
+
         try:
             from dateutil.parser import parse
-            parse_date = lambda x: parse(x, dayfirst=dayfirst)
+            parse_date = lambda x: parse(x, dayfirst=dayfirst, default=default)
         except ImportError: # pragma: no cover
             def parse_date(s):
                 try: