Bugzilla Bug 361332: use a better way to determine if $(NSPR_CO_TAG) can be

pulled by date. r=benjamin.smedberg

client.mk

@@ -600,11 +600,11 @@ ifdef MOZ_CO_FLAGS
 endif
 NSPR_CO_FLAGS := $(NSPR_CO_FLAGS) $(if $(NSPR_CO_TAG),-r $(NSPR_CO_TAG),-A)
 
-# Cannot pull static tags by date
-ifeq ($(NSPR_CO_TAG),NSPRPUB_CLIENT_TAG)
-CVSCO_NSPR = $(CVS) $(CVS_FLAGS) co $(NSPR_CO_FLAGS) $(NSPR_CO_MODULE)
-else
+# Can only pull the tip or branch tags by date
+ifeq (,$(filter-out HEAD %BRANCH,$(NSPR_CO_TAG)))
 CVSCO_NSPR = $(CVS) $(CVS_FLAGS) co $(NSPR_CO_FLAGS) $(CVS_CO_DATE_FLAGS) $(NSPR_CO_MODULE)
+else
+CVSCO_NSPR = $(CVS) $(CVS_FLAGS) co $(NSPR_CO_FLAGS) $(NSPR_CO_MODULE)
 endif
 
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