config: add a function in `rcutil` to abstract HGRCSKIPREPO

We wil need to respect this environment variable in more place.

Differential Revision: https://phab.mercurial-scm.org/D8072

mercurial/localrepo.py

@@ -53,6 +53,7 b' from . import ('
     phases,
     pushkey,
     pycompat,
+    rcutil,
     repoview,
     revset,
     revsetlang,
@@ -676,7 +677,7 b' def loadhgrc(ui, wdirvfs, hgvfs, require'
     configs are loaded. For example, an extension may wish to pull in
     configs from alternate files or sources.
     """
-    if b'HGRCSKIPREPO' in encoding.environ:
+    if not rcutil.use_repo_hgrc():
         return False
     try:
         ui.readconfig(hgvfs.join(b'hgrc'), root=wdirvfs.base)

mercurial/rcutil.py

@@ -112,3 +112,8 b' def defaultpagerenv():'
     intended to be set before starting a pager.
     '''
     return {b'LESS': b'FRX', b'LV': b'-c'}
+
+
+def use_repo_hgrc():
+    """True if repositories `.hg/hgrc` config should be read"""
+    return b'HGRCSKIPREPO' not in encoding.environ