fileset: do not traceback on invalid grep pattern

mercurial/fileset.py

@@ -256,8 +256,11 b' def grep(mctx, x):'
     """``grep(regex)``
     File contains the given regular expression.
     """
-    pat = getstring(x, _("grep requires a pattern"))
-    r = re.compile(pat)
+    try:
+        # i18n: "grep" is a keyword
+        r = re.compile(getstring(x, _("grep requires a pattern")))
+    except re.error, e:
+        raise error.ParseError(_('invalid match pattern: %s') % e)
     return [f for f in mctx.existing() if r.search(mctx.ctx[f].data())]
 
 _units = dict(k=2**10, K=2**10, kB=2**10, KB=2**10,

tests/test-fileset.t

@@ -89,3 +89,11 b' Test files properties'
   $ fileset 'binary()'
   bin
 
+  $ fileset 'grep("b{1}")'
+  b2
+  c1
+  b1
+  $ fileset 'grep("missingparens(")'
+  hg: parse error: invalid match pattern: unbalanced parenthesis
+  [255]
+