check-commit: allow foo_bar naming in functions

nameswithallthewordssmashedtogetherarehardtoread.
especiallyifenglishisnotyourprimarylanguage.

Let's align with the rest of the programming universe and
allow_the_use_of_underscores_in_names.

We took a hand poll at the 5.2 sprint regarding this change and
all but 1 person supported it. The person who didn't expressed
concerns around excessive API breakage if we mass renamed things.
But we're not planning to mass rename things for the sake of
renaming, so all should be well.

Differential Revision: https://phab.mercurial-scm.org/D2010

contrib/check-code.py

@@ -340,8 +340,6 b' commonpypats = ['
         ),
         (r'[^\n]\Z', "no trailing newline"),
         (r'(\S[ \t]+|^[ \t]+)\n', "trailing whitespace"),
-        #    (r'^\s+[^_ \n][^_. \n]+_[^_\n]+\s*=',
-        #     "don't use underbars in identifiers"),
         (
             r'^\s+(self\.)?[A-Za-z][a-z0-9]+[A-Z]\w* = ',
             "don't use camelcase in identifiers",

contrib/check-commit

@@ -39,12 +39,6 b' errors = ['
      "summary keyword should be most user-relevant one-word command or topic"),
     (afterheader + r".*\.\s*\n", "don't add trailing period on summary line"),
     (afterheader + r".{79,}", "summary line too long (limit is 78)"),
-    # Forbid "_" in function name.
-    #
-    # We skip the check for cffi related functions. They use names mapping the
-    # name of the C function. C function names may contain "_".
-    (r"\n\+[ \t]+def (?!cffi)[a-z]+_[a-z]",
-     "adds a function with foo_bar naming"),
 ]
 
 word = re.compile(r'\S')

tests/test-contrib-check-commit.t

@@ -130,6 +130,4 b' A patch with other errors:'
    This has no topic and ends with a period.
   7: don't add trailing period on summary line
    This has no topic and ends with a period.
-  20: adds a function with foo_bar naming
-   + def blah_blah(x):
   [1]