BUG: Timedelta.microseconds is rounded up if nanos>500

[jonyii]

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• (optional) I have confirmed this bug exists on the master branch of pandas.

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Note: Please read this guide detailing how to provide the necessary information for us to reproduce your bug.

Code Sample, a copy-pastable example

t = pd.Timedelta(501, unit='ns')
t.components
print("sec=%d, micro=%d, nano=%d"  % (t.seconds, t.microseconds, t.nanoseconds))

assert t.microseconds == 0, "This should be zero, right?"

Problem description

Timedelta.microseconds is rounded up based on nanos

Expected Output

t.microseconds == 0

Output of pd.show_versions()

INSTALLED VERSIONS

commit : None
python : 3.6.10.final.0
python-bits : 64
OS : Linux
OS-release : 4.14.138+
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : en_US.UTF-8
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.0.3
numpy : 1.18.1
pytz : 2019.3
dateutil : 2.8.1
pip : 20.0.2
setuptools : 45.1.0.post20200119
Cython : 0.29.16
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.11.0
IPython : 7.13.0
pandas_datareader: None
bs4 : None
bottleneck : None
fastparquet : None
gcsfs : None
lxml.etree : None
matplotlib : 3.2.1
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pytables : None
pytest : None
pyxlsb : None
s3fs : None
scipy : 1.4.1
sqlalchemy : 1.3.13
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
xlsxwriter : None
numba : None

[jonyii]

the rounding is not consistent either:

for nanos in [-501, 500, 501, 1499, 1500]:
    t = pd.Timedelta(nanos, unit='ns')
    print(f"input nanos={nanos}:\t  t.microseconds = {t.microseconds} t.nanoseconds = {t.nanoseconds}\t", t)

[mroeschke]

Thanks for the report. This is solved by #31380 and will be included in the 1.1 release (in a couple of months)