[Tilecache] cells not being calculated correctly for bounding box

[Matt Bartolome]

Hi,
I'm trying to seed a cache with a specific bounding box. Most of my
layers honor the extent and seed perfectly however with certain layers
tilecache does not calculate the cells correctly and always returns
0,0 which causes tilecache_seed.py to try to seed the entire bbox of
the layer intead of my specified one in tilecache_seed.py.

Here are some tilecache.cfg examples and tilecache_seed.py commands
I'm using. Does anybody know what can cause this issue?

#These are a couple that are going nuts:
################################

[62971931]
layers = 62971931
mapfile = mapnik-config/62971931.xml
metatile = true
srs = epsg:2230
metabuffer = 5
bbox = 6296999.495,1930999.505,6309000.495,1939000.505
debug = false
type = Mapnik

$ tilecache_seed.py 62971931 10 11
"6296999.495,1930999.505,6309000.495,1939000.505"
###### (0, 0, 10), (1024, 683, 10)
10 (000000, 000000) = (6296999.4950 1930999.5050 6297011.2147
1931011.2247) [0.0002s : 1250.005/s] 1/28085

[62971923]
layers = 62971923
mapfile = mapnik-config/62971923.xml
metatile = true
srs = epsg:2230
metabuffer = 5
bbox = 6296999.495,1922999.505,6309000.495,1931000.505
debug = false
type = Mapnik

$  tilecache_seed.py 62971923 10 11
"6296999.495,1922999.505,6309000.495,1931000.505"
###### (0, 0, 10), (1024, 683, 10)
10 (000000, 000000) = (6296999.4950 1922999.5050 6297011.2147
1923011.2247) [0.0002s : 1838.454/s] 1/28085

[62971939]
layers = 62971939
mapfile = mapnik-config/62971939.xml
metatile = true
srs = epsg:2230
metabuffer = 5
bbox = 6124093,1761898.25,6637898,2175848.75
debug = false
type = Mapnik

#These are fine
#############

$ tilecache_seed.py 62971939 10 11
"6296999.495,1938999.505,6309000.495,1947000.505"
###### (345, 353, 10), (369, 369, 10)
10 (000345, 000353) = (6297201.1299 1939020.4814 6297702.8926
1939522.2441) [0.0895s : 11.112/s] 1/20

[62731995]
layers = 62731995
mapfile = mapnik-config/62731995.xml
metatile = true
srs = epsg:2230
metabuffer = 5
bbox = 6124093,1761898.25,6637898,2175848.75
debug = false
type = Mapnik

$ tilecache_seed.py 62731995 10 11
"6272999.495,1994999.505,6285000.495,2003000.505"
###### (297, 465, 10), (321, 481, 10)
10 (000297, 000465) = (6273116.5205 1995217.9033 6273618.2832
1995719.6660) [0.0486s : 20.352/s] 1/20