Allocate object segments for the worst case object size

Fixes another case of #22

src/fellow_cache.c

@@ -2301,9 +2301,15 @@ fellow_busy_body_seg_alloc(struct fellow_busy *fbo,
 		assert(fbo->sz_estimate > fbo->sz_dskalloc);
 		spc = fbo->sz_estimate - fbo->sz_dskalloc;
 
-		if (fbo->nregion >= FCO_MAX_REGIONS - FCO_REGIONS_RESERVE)
-			// out of regions: keep spc, no cram
+		if (fbo->nregion >= FCO_MAX_REGIONS - FCO_REGIONS_RESERVE) {
+			// out of regions: no cram,
+			// if grown, assume worst, else keep spc
 			cram = 0;
+			if (fbo->grown) {
+				spc = fbo->fc->tune->objsize_max -
+				    fbo->sz_dskalloc;
+			}
+		}
 		else if (fbo->grown == 0 && (spc >> chunkbits) == 0)
 			// c-l or initial chunked - keep small req
 			(void)spc;