qimport: report filename in case of IOError

The old behaviour was to say "abort: unable to read" since the
patchname variable was always None.

hgext/mq.py

@@ -1494,7 +1494,7 b' class queue:'
                     else:
                         text = file(filename, 'rb').read()
                 except IOError:
-                    raise util.Abort(_("unable to read %s") % patchname)
+                    raise util.Abort(_("unable to read %s") % filename)
                 if not patchname:
                     patchname = normname(os.path.basename(filename))
                 self.check_reserved_name(patchname)

tests/test-mq-qimport

@@ -21,9 +21,13 b' echo "mq=" >> $HGRCPATH'
 echo "[diff]" >> $HGRCPATH
 echo "git=1" >> $HGRCPATH
 
-echo % build diff with CRLF
 hg init repo
 cd repo
+
+echo % qimport non-existing-file
+hg qimport non-existing-file
+
+echo % build diff with CRLF
 python ../writelines.py b 5 'a\n' 5 'a\r\n'
 hg ci -Am addb
 python ../writelines.py b 2 'a\n' 10 'b\n' 2 'a\r\n'

tests/test-mq-qimport.out

@@ -1,3 +1,5 b''
+% qimport non-existing-file
+abort: unable to read non-existing-file
 % build diff with CRLF
 adding b
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved