revset: stop lowercasing the regex pattern for 'author'

It was probably unintentional for regex, as the meaning of some sequences like
\S and \s is actually inverted by changing the case.  For backward compatibility
however, the matching is forced to case insensitive.

mercurial/revset.py

@@ -556,9 +556,9 b' def author(repo, subset, x):'
     """Alias for ``user(string)``.
     """
     # i18n: "author" is a keyword
-    n = encoding.lower(getstring(x, _("author requires a string")))
-    kind, pattern, matcher = _substringmatcher(n)
-    return subset.filter(lambda x: matcher(encoding.lower(repo[x].user())),
+    n = getstring(x, _("author requires a string"))
+    kind, pattern, matcher = _substringmatcher(n, casesensitive=False)
+    return subset.filter(lambda x: matcher(repo[x].user()),
                          condrepr=('<user %r>', n))
 
 @predicate('bisect(string)', safe=True)
@@ -2249,10 +2249,15 b' def subrepo(repo, subset, x):'
 
     return subset.filter(matches, condrepr=('<subrepo %r>', pat))
 
-def _substringmatcher(pattern):
-    kind, pattern, matcher = util.stringmatcher(pattern)
+def _substringmatcher(pattern, casesensitive=True):
+    kind, pattern, matcher = util.stringmatcher(pattern,
+                                                casesensitive=casesensitive)
     if kind == 'literal':
-        matcher = lambda s: pattern in s
+        if not casesensitive:
+            pattern = encoding.lower(pattern)
+            matcher = lambda s: pattern in encoding.lower(s)
+        else:
+            matcher = lambda s: pattern in s
     return kind, pattern, matcher
 
 @predicate('tag([name])', safe=True)

tests/test-revset.t

@@ -865,6 +865,17 b' test ancestors'
   7
   8
   9
+  $ log 'author(r"re:\S")'
+  0
+  1
+  2
+  3
+  4
+  5
+  6
+  7
+  8
+  9
   $ log 'branch(é)'
   8
   9