Add new failing test case for a bug in tiles(), update requirements.txt

.gitignore

@@ -72,3 +72,4 @@ package-lock.json
 node_modules
 .hypothesis
 .mailmap
+.venv

mercantile/__init__.py

@@ -497,7 +497,10 @@ def quadkey_to_tile(qk):
 
 
 def tiles(west, south, east, north, zooms, truncate=False):
-    """Get the tiles overlapped by a geographic bounding box
+    """Get the tiles overlapped by a geographic bounding box.
+
+    NOTE: Web Mercator tiles cannot latitudes beyond ±85.051129.  
+    This region is not represented in the returned tile set even if you request it.
 
     Parameters
     ----------
@@ -521,12 +524,26 @@ def tiles(west, south, east, north, zooms, truncate=False):
     if truncate:
         west, south = truncate_lnglat(west, south)
         east, north = truncate_lnglat(east, north)
-    if west > east:
-        bbox_west = (-180.0, south, east, north)
-        bbox_east = (west, south, 180.0, north)
-        bboxes = [bbox_west, bbox_east]
-    else:
-        bboxes = [(west, south, east, north)]
+
+    # Create our bbox.
+    bboxes = [(west, south, east, north)]
+    # If the bbox straddles a pole (north-south), split it in half.
+    new_bboxes = []
+    for w, s, e, n in bboxes:
+        if s > n:
+            new_bboxes += [(w, s, e, 90.0), (w, -90.0, e, n)]
+        else:
+            new_bboxes += [(w,s,e,n)]
+    bboxes = new_bboxes
+
+    # If the bboxes straddle the antimeridian (east-west), split them in half.
+    new_bboxes = []
+    for w, s, e, n in bboxes:
+        if w > e:
+            new_bboxes += [(-180.0, s, e, n), (w, s, 180.0, n)]
+        else:
+            new_bboxes += [(w,s,e,n)]
+    bboxes = new_bboxes
 
     for w, s, e, n in bboxes:
         # Clamp bounding values.

requirements.in

@@ -0,0 +1,26 @@
+attrs
+certifi
+chardet
+click
+coverage>=7.6.8
+coveralls>=4.0.1
+docopt
+hypothesis
+idna
+importlib-metadata
+iniconfig
+packaging
+pluggy
+py
+pydocstyle
+pyparsing
+pytest
+pytest-cov
+requests
+snowballstemmer
+sortedcontainers
+toml
+typing-extensions
+urllib3
+zipp
+setuptools==7.