Fixed issue 391 (nested break in except-stmts)

tests/exception/texceptionbreak.nim

@@ -0,0 +1,45 @@
+discard """
+  file: "tnestedbreak.nim"
+  output: "1\n2\n3\n4"
+"""
+
+# First variety
+try:
+  raise newException(EOS, "Problem")
+except EOS:
+  for y in [1, 2, 3]:
+    discard
+  try:
+    discard
+  except EOS:
+    discard
+echo "1"
+
+# Second Variety
+try:
+  raise newException(EOS, "Problem")
+except EOS:
+  for y in [1, 2, 3]:
+    discard
+  for y in [1, 2, 3]:
+    discard
+
+echo "2"
+
+# Third Variety
+try:
+  raise newException(EOS, "Problem")
+except EOS:
+  block:
+    break
+
+echo "3"
+
+# Fourth Variety
+block:
+  try:
+    raise newException(EOS, "Problem")
+  except EOS:
+    break
+
+echo "4"