Fix TypeError in parser's error-wrapping logic

AUTHORS.md

@@ -70,6 +70,7 @@ switch, and thus all their contributions are dual-licensed.
 - Lauren Oldja <oldja@MASKED> (gh: @loldja) **D**
 - Luca Ferocino <luca.ferox@MASKED> (gh: @lucaferocino) **D**
 - Mario Corchero <mcorcherojim@MASKED> (gh: @mariocj89) **R**
+- Mark Bailey <msb@MASKED> **D**
 - Mateusz Dziedzic (gh: @m-dz) **D**
 - Matt Cooper <vtbassmatt@MASKED> (gh: @vtbassmatt) **D**
 - Matthew Schinckel <matt@MASKED>

changelog.d/987.bugfix.rst

@@ -0,0 +1,4 @@
+Fixed a bug in the parser where non-``ValueError`` exceptions would be raised
+during exception handling; this would happen, for example, if an
+``IllegalMonthError`` was raised in ``dateutil`` code. Fixed by Mark Bailey.
+(gh issue #981, pr #987).

dateutil/parser/_parser.py

@@ -654,7 +654,7 @@ def parse(self, timestr, default=None,
         try:
             ret = self._build_naive(res, default)
         except ValueError as e:
-            six.raise_from(ParserError(e.args[0] + ": %s", timestr), e)
+            six.raise_from(ParserError(str(e) + ": %s", timestr), e)
 
         if not ignoretz:
             ret = self._build_tzaware(ret, res, tzinfos)

dateutil/test/test_parser.py

@@ -743,6 +743,10 @@ def test_out_of_bound_day(self):
         with pytest.raises(ParserError):
             parse("Feb 30, 2007")
 
+    def test_illegal_month_error(self):
+        with pytest.raises(ParserError):
+            parse("0-100")
+
     def test_day_sanity(self, fuzzy):
         dstr = "2014-15-25"
         with pytest.raises(ParserError):