global: use raw strings for regular expressions with escapes

Escape sequences like \w, \s, and \d are technically invalid
in str/bytes. This became a deprecation warning in Python 3.6
(https://bugs.python.org/issue27364). Python 3.8 bumps it to
a SyntaxWarning (https://bugs.python.org/issue32912), which is
non-silent by default.

This commit changes a number of regular expressions to use
br'' so regular expression special sequences don't need \\
literals. This fixes roughly half of the SyntaxWarning we
see in the code base with Python 3.8.

Differential Revision: https://phab.mercurial-scm.org/D5815

hgext/blackbox.py

@@ -190,7 +190,7 b' def blackbox(ui, repo, *revs, **opts):'
             break
 
         # count the commands by matching lines like: 2013/01/23 19:13:36 root>
-        if re.match('^\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2} .*> .*', line):
+        if re.match(br'^\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2} .*> .*', line):
             count += 1
         output.append(line)
 

hgext/commitextras.py

@@ -58,7 +58,7 b' def _commit(orig, ui, repo, *pats, **opt'
                 if not k:
                     msg = _("unable to parse '%s', keys can't be empty")
                     raise error.Abort(msg % raw)
-                if re.search('[^\w-]', k):
+                if re.search(br'[^\w-]', k):
                     msg = _("keys can only contain ascii letters, digits,"
                             " '_' and '-'")
                     raise error.Abort(msg)

hgext/convert/cvsps.py

@@ -122,7 +122,7 b' def createlog(ui, directory=None, root="'
     re_31 = re.compile(b'----------------------------$')
     re_32 = re.compile(b'======================================='
                        b'======================================$')
-    re_50 = re.compile(b'revision ([\\d.]+)(\s+locked by:\s+.+;)?$')
+    re_50 = re.compile(br'revision ([\d.]+)(\s+locked by:\s+.+;)?$')
     re_60 = re.compile(br'date:\s+(.+);\s+author:\s+(.+);\s+state:\s+(.+?);'
                        br'(\s+lines:\s+(\+\d+)?\s+(-\d+)?;)?'
                        br'(\s+commitid:\s+([^;]+);)?'

hgext/mq.py

@@ -1181,7 +1181,7 b' class queue(object):'
     def makepatchname(self, title, fallbackname):
         """Return a suitable filename for title, adding a suffix to make
         it unique in the existing list"""
-        namebase = re.sub('[\s\W_]+', '_', title.lower()).strip('_')
+        namebase = re.sub(br'[\s\W_]+', b'_', title.lower()).strip(b'_')
         namebase = namebase[:75] # avoid too long name (issue5117)
         if namebase:
             try:

hgext/phabricator.py

@@ -255,9 +255,9 b' def getrepophid(repo):'
     repo.ui.setconfig(b'phabricator', b'repophid', repophid)
     return repophid
 
-_differentialrevisiontagre = re.compile(b'\AD([1-9][0-9]*)\Z')
+_differentialrevisiontagre = re.compile(br'\AD([1-9][0-9]*)\Z')
 _differentialrevisiondescre = re.compile(
-    b'^Differential Revision:\s*(?P<url>(?:.*)D(?P<id>[1-9][0-9]*))$', re.M)
+    br'^Differential Revision:\s*(?P<url>(?:.*)D(?P<id>[1-9][0-9]*))$', re.M)
 
 def getoldnodedrevmap(repo, nodelist):
     """find previous nodes that has been sent to Phabricator

hgext/releasenotes.py

@@ -55,7 +55,7 b' DEFAULT_SECTIONS = ['
     ('api', _('API Changes')),
 ]
 
-RE_DIRECTIVE = re.compile('^\.\. ([a-zA-Z0-9_]+)::\s*([^$]+)?$')
+RE_DIRECTIVE = re.compile(br'^\.\. ([a-zA-Z0-9_]+)::\s*([^$]+)?$')
 RE_ISSUE = br'\bissue ?[0-9]{4,6}(?![0-9])\b'
 
 BULLET_SECTION = _('Other Changes')

mercurial/color.py

@@ -484,7 +484,7 b' if pycompat.iswindows:'
             w32effects = None
         else:
             origattr = csbi.wAttributes
-            ansire = re.compile(b'\033\[([^m]*)m([^\033]*)(.*)',
+            ansire = re.compile(br'\033\[([^m]*)m([^\033]*)(.*)',
                                 re.MULTILINE | re.DOTALL)
 
     def win32print(ui, writefunc, text, **opts):

mercurial/patch.py

@@ -638,8 +638,8 b' class repobackend(abstractbackend):'
         return self.changed | self.removed
 
 # @@ -start,len +start,len @@ or @@ -start +start @@ if len is 1
-unidesc = re.compile('@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@')
-contextdesc = re.compile('(?:---|\*\*\*) (\d+)(?:,(\d+))? (?:---|\*\*\*)')
+unidesc = re.compile(br'@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@')
+contextdesc = re.compile(br'(?:---|\*\*\*) (\d+)(?:,(\d+))? (?:---|\*\*\*)')
 eolmodes = ['strict', 'crlf', 'lf', 'auto']
 
 class patchfile(object):
@@ -2762,7 +2762,7 b' def diffstatsum(stats):'
     return maxfile, maxtotal, addtotal, removetotal, binary
 
 def diffstatdata(lines):
-    diffre = re.compile('^diff .*-r [a-z0-9]+\s(.*)$')
+    diffre = re.compile(br'^diff .*-r [a-z0-9]+\s(.*)$')
 
     results = []
     filename, adds, removes, isbinary = None, 0, 0, False