Fix incorrect local coverage result with package level minimum

[andy-maier]

One run where that can be seen is on Python 3.8 with minimum package level,
https://travis-ci.org/github/pywbem/pywbemtools/jobs/666994594#L2092:

----------- coverage: platform linux, python 3.8.0-final-0 -----------
Name                                              Stmts   Miss  Cover   Missing
-------------------------------------------------------------------------------
pywbemtools/pywbemcli/__init__.py                    19      0   100%
pywbemtools/pywbemcli/_association_shrub.py         375    220    41%   62, 142, 342, 380, 384, 484, 486, 530-537, 562, 569, 575-576, 580, 584-585, 591, 607, 707, 728, 739-742, 746-747, 764, 766, 792-794, 798, 815, 838, 868, 870-3187
pywbemtools/pywbemcli/_cimvalueformatter.py         184    120    35%   31-32, 40, 118-120, 379, 426-428, 519-8247
pywbemtools/pywbemcli/_click_extensions.py           20      1    95%   31
pywbemtools/pywbemcli/_cmd_class.py                 375    237    37%   571, 736-737, 803, 897-5213
pywbemtools/pywbemcli/_cmd_connection.py            224    114    49%   309, 336, 377, 380, 399, 481-482, 545, 626-1999
pywbemtools/pywbemcli/_cmd_instance.py              540    418    23%   562, 735, 742, 749-751, 758-789, 818, 843, 916, 964, 1014-1017, 1041, 1077, 1084, 1087, 1127, 1138, 1155-1156, 1177-1183, 1236, 1252-11210
pywbemtools/pywbemcli/_cmd_qualifier.py              47     30    36%   311-897
pywbemtools/pywbemcli/_cmd_server.py                190    113    41%   207, 287, 324-325, 360, 480-2409
pywbemtools/pywbemcli/_common.py                    582    179    69%   115, 125-127, 175, 283, 325, 340, 349-350, 396, 403-406, 497-498, 505, 507, 509, 513, 521, 548-549, 671, 673, 709-713, 716-717, 760-764, 768, 772, 774, 779, 808, 838, 840, 842-845, 910, 913, 1033-1059, 1104-1106, 1144, 1168, 1170, 1173, 1188-1194, 1265-1267, 1317, 1325-1326, 1363-1401, 1405-1406, 1422, 1426, 1428, 1433, 1436, 1439, 1459, 1465, 1558, 1561, 1565, 1600, 1619-2881
pywbemtools/pywbemcli/_common_options.py             60     51    15%   287-5749
pywbemtools/pywbemcli/_connection_repository.py     143     71    50%   33, 101-105, 115-116, 122, 153-154, 232, 295, 323-1975
pywbemtools/pywbemcli/_context_obj.py               177     89    50%   63, 212, 239, 257-258, 287, 293, 369-373, 405-411, 421-2134
pywbemtools/pywbemcli/_displaytree.py                37      5    86%   63, 369-375
pywbemtools/pywbemcli/_pywbem_server.py             215    120    44%   56, 119, 141, 252, 254, 322, 387, 430-440, 454-461, 469, 480-483, 496-3053
pywbemtools/pywbemcli/_pywbemcli_operations.py      118     80    32%   309, 345-347, 400-2052
pywbemtools/pywbemcli/_utils.py                      16      7    56%   41, 53, 65-69
pywbemtools/pywbemcli/config.py                      14     12    14%   298-360
pywbemtools/pywbemcli/pywbemcli.py                  372    325    13%   61-62, 318, 333-334, 561, 577-579, 586-588, 593-594, 643, 646-10347
-------------------------------------------------------------------------------
TOTAL                                              3708   2192    41%

One thing that can be seen is that the reported missing line numbers for some files are above the line numbers of the files. For example:

• pywbemtools/pywbemcli/_association_shrub.py: reports missing lines up to 3187, but has only 870 lines.

For comparison, here is the result of the same PR on python 3.8 with latest package levels,
https://travis-ci.org/github/pywbem/pywbemtools/jobs/666994595#L1978:

----------- coverage: platform linux, python 3.8.0-final-0 -----------
Name                                              Stmts   Miss  Cover   Missing
-------------------------------------------------------------------------------
pywbemtools/pywbemcli/__init__.py                    19      0   100%
pywbemtools/pywbemcli/_association_shrub.py         324     46    86%   62, 142, 291-292, 351, 486, 530-537, 562, 569, 575-576, 580, 584-585, 591, 607, 616-645, 728-730, 792-794, 798, 819, 838
pywbemtools/pywbemcli/_cimvalueformatter.py         110     14    87%   31-32, 40, 118-120, 169-173, 193-197, 426, 494
pywbemtools/pywbemcli/_click_extensions.py           20      1    95%   31
pywbemtools/pywbemcli/_cmd_class.py                 292      9    97%   736-737, 745-746, 800-801, 885, 892-893
pywbemtools/pywbemcli/_cmd_connection.py            191      8    96%   309, 380, 435-441, 481-482, 545
pywbemtools/pywbemcli/_cmd_instance.py              369     35    91%   742, 749-751, 758, 763, 776-781, 789, 818, 843, 874-875, 893-894, 916, 929-931, 964, 1041, 1087, 1118, 1138, 1155-1156, 1177-1178, 1219, 1236, 1250-1251
pywbemtools/pywbemcli/_cmd_qualifier.py              37      0   100%
pywbemtools/pywbemcli/_cmd_server.py                139     19    86%   207, 228-229, 247-248, 265-266, 287, 297-298, 324-325, 357-358, 392-394, 405-406
pywbemtools/pywbemcli/_common.py                    616     71    88%   115, 125-127, 175, 257-260, 283, 288-289, 294-295, 325, 340, 349-350, 403-404, 497, 585-586, 671, 673, 760-764, 768, 774, 808, 813, 899, 924, 1018, 1024-1026, 1032-1033, 1039-1045, 1058-1059, 1105-1106, 1168, 1170, 1188-1194, 1265-1267, 1289, 1317, 1363, 1422, 1426, 1433, 1439, 1459, 1465, 1472, 1558, 1561, 1565
pywbemtools/pywbemcli/_common_options.py             20      0   100%
pywbemtools/pywbemcli/_connection_repository.py     113     19    83%   33, 70, 76, 101-105, 115-116, 122, 153-154, 178-183, 232, 295
pywbemtools/pywbemcli/_context_obj.py               157     35    78%   63, 161, 201-204, 212, 239, 257-260, 265-266, 287, 293, 304, 309, 325-328, 337, 369-373, 405-411, 421-428
pywbemtools/pywbemcli/_displaytree.py                36      1    97%   63
pywbemtools/pywbemcli/_pywbem_server.py             197     17    91%   56, 65, 119, 141, 252, 254, 347, 429-430, 436, 439, 457, 463-466, 479-480
pywbemtools/pywbemcli/_pywbemcli_operations.py       61      2    97%   284, 309
pywbemtools/pywbemcli/_utils.py                      16      7    56%   41, 53, 65-69
pywbemtools/pywbemcli/config.py                      13      0   100%
pywbemtools/pywbemcli/pywbemcli.py                  215     13    94%   61-62, 318, 352-359, 535-536, 565, 575, 586-588
-------------------------------------------------------------------------------
TOTAL                                              2945    297    90%

The same PR on Python 2.7 with minimum(!) package levels reports reasonable coverage and line numbers.

[andy-maier]

The issue seems to be related to the version of the coverage package. On a local Python 3.8 on MacOS, the issue behaves as follows:

• PACKAGE_LEVEL=minimum (coverage 4.5): issue shows up
• PACKAGE_LEVEL=latest (coverage 4.5.4): issue does not show up
• PACKAGE_LEVEL=latest, coverage downgraded to 4.5: issue shows up
• PACKAGE_LEVEL=latest, coverage downgraded to 4.5.3: issue does not show up
• PACKAGE_LEVEL=latest, coverage downgraded to 4.5.2: issue does not show up
• PACKAGE_LEVEL=latest, coverage downgraded to 4.5.1: issue shows up

This means the issue is caused by the coverage package, and was fixed in coverage 4.5.2
(change log of coverage). The corresponding issue is nedbat/coveragepy#714.

The solution is therefore to increase the minimum version of coverage to 4.5.2.

[andy-maier]

Addressed in PR #550 for master.