Rebalance fails if bucket replication is in mixed tap/dcp state

Found this in the logs from CBSE-1626:

[error_logger:error,2015-01-21T18:53:10.887,ns_1@nodename:error_logger<0.6.0>:ale_error_logger_handler:do_log:203]
=========================CRASH REPORT=========================
crasher:
initial call: ns_single_vbucket_mover:mover/6
pid: <0.4067.568>
registered_name: []
exception error: no case clause matching
{true,{dcp,[150,151,152,153,154,155,156,157,158,164,175,
176,177,178,181,182,183,184,185,211,212,213,
217,218,219,236,237,254,255,256,257,258,259,
260,261,262,263,264,268,272,273,275,276,277,
278,279,280,287,288,289,293,294,295,296,297,
298,299,300,301,302,304,305,306,307,308,312,
313,314,315,316,317,318,319,330,331,332,333,
334,335,336,337,338,339,341,342,343,344,345,
348,349,350,351,352,353,354,355,356,357,358,
359,360,361,362,363,364,366,367,368,369,370,
371,372,373,374,375,376,377,378,379,380,381,
382,383,384,385,386,387,388,389,402,403,404,
405,415,416,417,418,419,420,421,422,423,424,
425,426,427,428,429,430,431,432,433,434,435,
436,437,438,439,440,441,442,443,444,451,454,
455,456,457,458,459,460,461,462,463,464,465,
466,467,471,472,473,474,475,476,477,478,479,
481,482,484,486,488,489,490,491,492,493,494,
495,496,497,498,499,500,501,502,503,507,508,
509,510,511,512,514,515,516,517,518,519,520,
521,522,523,524,525,526,527,530,531,532,538,
539,540,541,542,543,544,545,546,547,548,549,
550,551,552,553,554,555,556,557,558,559,560,
561,562,563,564,565,566,567,568,569,570,571,
572,573,575,576,577,578,579,580,581,582,591,
592,593,594,595,596,597,598,599,600,601,602,
603,604,605,606,607,608,613,614,615,616,617,
618,619,620,622,623,626,628,629,630,631,632,
633,634,635,636,637,638,639,640,641,642,643,
644,645,646,647,648,649,650,651,652,653,654,
655,656,657,658,659,660,661,662,663,664,665,
666,667,668,669,670,671,672,673,674,675,676,
677,678,679,680,681,682,683,684,685,686,687,
688,689,690,691,692,693,694,695,696,697,698,
699,700,701,702,703,704,705,706,707,708,709,
710,711,712,713,714,715,716,717,718,719,720,
721,722,723,724,725,726,727,728,729,730,731,
732,733,734,735,736,737,738,739,740,741,742,
743,744,745,746,747,748,749,750,751,752,753,
754,755,756,757,758,759,760,761,762,763,764,
765,766,767,768,769,770,771,772,773,774,775,
776,777,778,779,780,781,782,783,784,785,786,
787,788,789,790,791,792,793,794,795,796,797,
798,799,800,801,802,803,804,805,806,807,808,
809,810,811,812,813,814,815,816,817,818,819,
820,821,822,823,824,825,826,827,828,829,830,
831,832,833,834,835,836,837,838,839,840,841,
842,843,844,845,846,847,848,849,850,851,852,
853,854,855,856,857,858,859,860,861,862,863,
864,865,866,867,868,869,870,871,872,873,874,
875,876,877,878,879,880,881,882,883,884,885,
886,887,888,889,890,891,892,893,894,895,896,
897,898,899,900,901,902,903,904,905,906,907,
908,909,910,911,912,913,914,915,916,917,918,
919,920,921,922,923,924,925,926,927,928,929,
930,931,932,933,934,935,936,937,938,939,940,
941,942,943,944,945,946,947,948,949,950,951,
952,953,954,955,956,957,958,959,960,961,962,
963,964,965,966,967,968,969,970,971,972,973,
974,975,976,977,978,979,980,981,982,983,984,
985,986,987,988,989,990,991,992,993,994,995,
996,997,998,999,1000,1001,1002,1003,1004,
1005,1006,1007,1008,1009,1010,1011,1012,1013,
1014,1015,1016,1017,1018,1019,1020,1021,1022,
1023]}}
in function ns_single_vbucket_mover:'mover/6-fun-2'/7 (src/ns_single_vbucket_mover.erl, line 79)
in call from misc:try_with_maybe_ignorant_after/2 (src/misc.erl, line 1465)
in call from ns_single_vbucket_mover:mover/6 (src/ns_single_vbucket_mover.erl, line 77)
ancestors: [<0.3942.568>,<0.3666.568>,<0.1772.0>,mb_master_sup,
mb_master,ns_server_sup,ns_server_cluster_sup,<0.59.0>]
messages: []
links: [<0.3942.568>]
dictionary: []
trap_exit: false
status: running
heap_size: 2586
stack_size: 27
reductions: 2626
neighbours: