wrong time prefixes on file names

[idallen]

The time prefixes on the message file names generated with -t (use envelope timestamp) are off by one name. The time stamp used to name the current message file is the time stamp of the previous message file. The first message file, having no previous time stamp, is missing the leading time stamp. The modification times of the message files are set correctly; only the names are off-by-one.

$ ./mb2md.pl -S -t -m -d foo
[...]
28092 messages.

$ find foo/new -type f -printf '%T@  %f\n' | head
1088656864.0000000000  1733138021.000000.mbox,S=6215:2,S
1090650675.0000000000  1088656864-1733138021.000001.mbox,S=4254:2,S
1092261667.0000000000  1090650675-1733138021.000002.mbox,S=5627:2,S
1092620882.0000000000  1092261667-1733138021.000003.mbox,S=7573:2,S
1095337264.0000000000  1092620882-1733138021.000004.mbox,S=19384:2,RS
1095343564.0000000000  1095337264-1733138021.000005.mbox,S=10747:2,RS
1108069867.0000000000  1095343564-1733138021.000006.mbox,S=3082:2,S
1108931944.0000000000  1108069867-1733138021.000007.mbox,S=3416:2,RS
1122610266.0000000000  1108931944-1733138021.000008.mbox,S=17709:2,RS
1122654065.0000000000  1122610266-1733138021.000009.mbox,S=3510:2,RS

Note that the incorrect leading time field on each message file name, except the first, is the modification time of the previous message file. The leading time field should be modification time of the message itself, not of the previous message. This is also true under foo/cur:

$ find foo/cur -type f -printf '%T@  %f\n' | head
1233599477.0000000000  1232548864-1733138021.000050.mbox,S=3856:2,S
1234325462.0000000000  1233599477-1733138021.000051.mbox,S=5728:2,S
1234326062.0000000000  1234325462-1733138021.000052.mbox,S=5958:2,S
1234588863.0000000000  1234326062-1733138021.000053.mbox,S=2275:2,S
1234588862.0000000000  1234588863-1733138021.000054.mbox,S=7608:2,S
1234983075.0000000000  1234588862-1733138021.000055.mbox,S=4260:2,RS
1236186063.0000000000  1234983075-1733138021.000056.mbox,S=5969:2,RS
1236208263.0000000000  1236186063-1733138021.000057.mbox,S=4926:2,S
1238711464.0000000000  1236208263-1733138021.000058.mbox,S=4741:2,RS
1238714464.0000000000  1238711464-1733138021.000059.mbox,S=5152:2,S

This happens because the $messagefn is used to create the new message file before the $filebase is set to the correct prefix. $filebase is only set after the file is closed. The fix is to move the code to set $filebase up to where $receivedate is set, before the message file is opened.