Move -MERGING- string to a constant.

Remove extra whitespace.
diff --git a/pym/portage/const.py b/pym/portage/const.py
index 1785bff..50f0719 100644
--- a/pym/portage/const.py
+++ b/pym/portage/const.py
@@ -74,6 +74,7 @@
 PRELINK_BINARY           = "/usr/sbin/prelink"
 
 INVALID_ENV_FILE         = "/etc/spork/is/not/valid/profile.env"
+MERGING_IDENTIFIER       = "-MERGING-"
 REPO_NAME_FILE           = "repo_name"
 REPO_NAME_LOC            = "profiles" + "/" + REPO_NAME_FILE
 
diff --git a/pym/portage/dbapi/__init__.py b/pym/portage/dbapi/__init__.py
index a20a1e8..6638352 100644
--- a/pym/portage/dbapi/__init__.py
+++ b/pym/portage/dbapi/__init__.py
@@ -16,6 +16,8 @@
 	'portage.versions:catsplit,catpkgsplit,vercmp,_pkg_str',
 )
 
+from portage.const import MERGING_IDENTIFIER
+
 from portage import os
 from portage import auxdbkeys
 from portage.eapi import _get_eapi_attrs
@@ -278,7 +280,7 @@
 		return True
 
 	def invalidentry(self, mypath):
-		if '/-MERGING-' in mypath:
+		if MERGING_IDENTIFIER in mypath:
 			if os.path.exists(mypath):
 				writemsg(colorize("BAD", _("INCOMPLETE MERGE:"))+" %s\n" % mypath,
 					noiselevel=-1)
diff --git a/pym/portage/dbapi/vartree.py b/pym/portage/dbapi/vartree.py
index 4a27092..1984a66 100644
--- a/pym/portage/dbapi/vartree.py
+++ b/pym/portage/dbapi/vartree.py
@@ -45,7 +45,7 @@
 )
 
 from portage.const import CACHE_PATH, CONFIG_MEMORY_FILE, \
-	PORTAGE_PACKAGE_ATOM, PRIVATE_PATH, VDB_PATH
+	MERGING_IDENTIFIER, PORTAGE_PACKAGE_ATOM, PRIVATE_PATH, VDB_PATH
 from portage.dbapi import dbapi
 from portage.exception import CommandNotFound, \
 	InvalidData, InvalidLocation, InvalidPackageName, \
@@ -104,7 +104,7 @@
 
 	_excluded_dirs = ["CVS", "lost+found"]
 	_excluded_dirs = [re.escape(x) for x in _excluded_dirs]
-	_excluded_dirs = re.compile(r'^(\..*|-MERGING-.*|' + \
+	_excluded_dirs = re.compile(r'^(\..*|' + MERGING_IDENTIFIER + '.*|' + \
 		"|".join(_excluded_dirs) + r')$')
 
 	_aux_cache_version        = "1"
@@ -446,7 +446,7 @@
 				if self._excluded_dirs.match(y) is not None:
 					continue
 				subpath = x + "/" + y
-				# -MERGING- should never be a cpv, nor should files.
+				# MERGING_IDENTIFIER should never be a cpv, nor should files.
 				try:
 					if catpkgsplit(subpath) is None:
 						self.invalidentry(self.getpath(subpath))
@@ -1504,7 +1504,7 @@
 		self.dbroot = normalize_path(os.path.join(self._eroot, VDB_PATH))
 		self.dbcatdir = self.dbroot+"/"+cat
 		self.dbpkgdir = self.dbcatdir+"/"+pkg
-		self.dbtmpdir = self.dbcatdir+"/-MERGING-"+pkg
+		self.dbtmpdir = self.dbcatdir+MERGING_IDENTIFIER+pkg
 		self.dbdir = self.dbpkgdir
 		self.settings = mysettings
 		self._verbose = self.settings.get("PORTAGE_VERBOSE") == "1"