GBTFITSLoad.write() can write bad intnum's and the multifile=False does not always work

[teuben]

Describe the bug
This started out as a case where multifile=False caused in index error, but when playing with more options, when it did work, it would write bad intnums. See example below.

How to Reproduce

The snippet of code has 4 cases, 1 fails, 2 are suspect (bad intnum's)

from dysh.util import get_project_testdata

fn = get_project_testdata() / "AGBT18B_354_03/AGBT18B_354_03.raw.vegas"

sdf=GBTFITSLoad(fn)
sdf.write("write_test1.fits", ifnum=0, overwrite=True, multifile=False)   # fails  'list index out of range'
sdf.write("write_test2.fits", plnum=0, overwrite=True, multifile=False)   # ok  write_test1.fits (multiHDU)
sdf.write("write_test3.fits", plnum=0, overwrite=True)                    # ok, write_test10,11,12,13.fits
sdf.write("write_test4.fits", plnum=0, overwrite=True, multifile=False)   # write_test1.fits
sdf.summary()
sdf.summary(verbose=True)

sdf1 = GBTFITSLoad("write_test1.fits")    **# this failed to write (the index error)**
sdf1.summary()
sdf1.summary(verbose=True)

sdf2 = GBTFITSLoad("write_test2.fits")  #   4 HDU's, each one an IF
sdf2.summary()
sdf2.summary(verbose=True)    **# has bad intnum's**


sdf3 = GBTFITSLoad("write_test30.fits")
sdf3.summary()
sdf3.summary(verbose=True)

sdf4 = GBTFITSLoad("write_test4.fits")     #   4 HDU's
sdf4.summary()
sdf4.summary(verbose=True)   **# has bad intnums**

Environment

• Dysh version 0.4.0
• Python version 3.12.4
• OS ubuntu 22.04

[mpound]

in gbtfitsload.write() I think this line
hdu = self._sdf[fi[0]]._hdu[fi[0]].copy()
should be
hdu = self._sdf[fi[0]]._hdu[0].copy()

[teuben]

yes, a lot better. still not all intnum values makes sense. looking into it.