lstrip remove extra characters in the presence of a matching number

[AkileshK]

BPO	37114
Nosy	@tiran

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2019-05-31.12:43:05.660>
created_at = <Date 2019-05-31.12:40:18.278>
labels = ['type-bug', 'invalid']
title = 'lstrip remove extra characters in the presence of a matching number'
updated_at = <Date 2019-05-31.12:43:05.657>
user = 'https://bugs.python.org/AkileshK'

bugs.python.org fields:

activity = <Date 2019-05-31.12:43:05.657>
actor = 'christian.heimes'
assignee = 'none'
closed = True
closed_date = <Date 2019-05-31.12:43:05.660>
closer = 'christian.heimes'
components = []
creation = <Date 2019-05-31.12:40:18.278>
creator = 'Akilesh K'
dependencies = []
files = []
hgrepos = []
issue_num = 37114
keywords = []
message_count = 2.0
messages = ['344070', '344072']
nosy_count = 2.0
nosy_names = ['christian.heimes', 'Akilesh K']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue37114'
versions = ['Python 2.7', 'Python 3.5']

[AkileshK]

When the argument to lstrip / strip has a number and it matches the string it begins to act different.

>>> text = "apiv1appliance"
>>> text.strip("apiv1")
'liance'
>>> text.strip("apiv2")
'1appliance'
>>> text.strip("a")
'piv1appliance'
>>> text.strip("ap")
'iv1appliance'
>>> text.strip("api")
'v1appliance'
>>> text.strip("apiv")
'1appliance'
>>> text.strip("apiv1")
'liance'
>>> text.strip("apiv2")
'1appliance'

[tiran]

It's not a bug. strip() does not work like you think. Please read the documentation https://docs.python.org/3/library/stdtypes.html?highlight=strip#str.strip