bpo-31677: email: Remove re.IGNORECASE flag (GH-3868)

While there is not real bug in this case, using re.IGNORECASE without re.ASCII
leads unexpected behavior.
Instead of adding re.ASCII, this commit removes re.IGNORECASE flag because
it's easier and simpler.

This commit removes dead copy of the pattern in email.util module too.
While the pattern is same, it is compiled separately because it had different flags.

diff --git a/Lib/email/header.py b/Lib/email/header.py
index c7b2dd9f310b01ca7e2f8c08f0a7fe5138fe4d6f..7b30a039da1c46e03f366ae2ff362eb717cbc10c 100644 (file)
--- a/Lib/email/header.py
+++ b/Lib/email/header.py
@@ -36,11 +36,11 @@ ecre = re.compile(r'''
   =\?                   # literal =?
   (?P<charset>[^?]*?)   # non-greedy up to the next ? is the charset
   \?                    # literal ?
-  (?P<encoding>[qb])    # either a "q" or a "b", case insensitive
+  (?P<encoding>[qQbB])  # either a "q" or a "b", case insensitive
   \?                    # literal ?
   (?P<encoded>.*?)      # non-greedy up to the next ?= is the encoded string
   \?=                   # literal ?=
-  ''', re.VERBOSE | re.IGNORECASE | re.MULTILINE)
+  ''', re.VERBOSE | re.MULTILINE)
 
 # Field name regexp, including trailing colon, but not separating whitespace,
 # according to RFC 2822.  Character range is from tilde to exclamation mark.

diff --git a/Lib/email/utils.py b/Lib/email/utils.py
index 39c22406078074dd6f03db166924721241c1ad02..858f620e25bfb0127c35e62aad22b6bfd33ad0de 100644 (file)
--- a/Lib/email/utils.py
+++ b/Lib/email/utils.py
@@ -114,18 +114,6 @@ def getaddresses(fieldvalues):
     return a.addresslist
 
 
-
-ecre = re.compile(r'''
-  =\?                   # literal =?
-  (?P<charset>[^?]*?)   # non-greedy up to the next ? is the charset
-  \?                    # literal ?
-  (?P<encoding>[qb])    # either a "q" or a "b", case insensitive
-  \?                    # literal ?
-  (?P<atom>.*?)         # non-greedy up to the next ?= is the atom
-  \?=                   # literal ?=
-  ''', re.VERBOSE | re.IGNORECASE)
-
-
 def _format_timetuple_and_zone(timetuple, zone):
     return '%s, %02d %s %04d %02d:%02d:%02d %s' % (
         ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'][timetuple[6]],