re2: make errors quiet

By default, the re2 library will output error on its own instead of keeping the
error in an exception. This make re2 printing spurious error before fallback to
the stdlib remodule that may accept the pattern or also fails to parse it and
raise a proper error that will be handled by Mercurial.

So we also pass an Option object that changes this default.

mercurial/util.py

@@ -2196,6 +2196,8 b' def fscasesensitive(path: bytes) -> bool'
 
 
 _re2_input = lambda x: x
+# google-re2 will need to be tell to not output error on its own
+_re2_options = None
 try:
     import re2  # pytype: disable=import-error
 
@@ -2216,6 +2218,7 b' class _re:'
     def _checkre2():
         global _re2
         global _re2_input
+        global _re2_options
         if _re2 is not None:
             # we already have the answer
             return
@@ -2234,6 +2237,12 b' class _re:'
             check_input = pycompat.sysstr(check_input)
             _re2 = bool(re2.match(check_pattern, check_input))
             _re2_input = pycompat.sysstr
+        try:
+            quiet = re2.Options()
+            quiet.log_errors = False
+            _re2_options = quiet
+        except AttributeError:
+            pass
 
     def compile(self, pat, flags=0):
         """Compile a regular expression, using re2 if possible
@@ -2249,7 +2258,12 b' class _re:'
             if flags & remod.MULTILINE:
                 pat = b'(?m)' + pat
             try:
-                return re2.compile(_re2_input(pat))
+                input_regex = _re2_input(pat)
+                if _re2_options is not None:
+                    compiled = re2.compile(input_regex, options=_re2_options)
+                else:
+                    compiled = re2.compile(input_regex)
+                return compiled
             except re2.error:
                 pass
         return remod.compile(pat, flags)