r.contour started producing broken/segmented contour lines since 7.4

[metello]

Since GRASS 7.4, some contour lines generated by r.contour are broken into several segments (until 7.2 was ok). I have a system that uses r.contour to trace reservoirs for hydroelectric plants and that problem is breaking my algorithm. In the attached GRASS project, you can see the result generated by different GRASS versions (contour level = 229) - look at the largest contour line. I tested the following versions: 7.2.3, 7.4.4, 7.6 and 7.7svn. Only 7.2.3 produced a continuous/unbroken contour.

[metello]

The file was too large to attach. I uploaded here: ​http://psr-shared.s3.amazonaws.com/public/admin/2C66EC59/R_CONTOUR_BUG.zip

Coordinates of some points of discontinuity: (384073.870002,8827636.45371), (402242.43372,8799021.33681), (409632.732253,8796197.58953)

[mmetz]

Replying to metello:

The file was too large to attach. I uploaded here: ​http://psr-shared.s3.amazonaws.com/public/admin/2C66EC59/R_CONTOUR_BUG.zip

Coordinates of some points of discontinuity: (384073.870002,8827636.45371), (402242.43372,8799021.33681), (409632.732253,8796197.58953)

I can confirm the missing segments, the previous fix to prevent contours from tracing back on themselves was not working. Working on it...

[mmetz]

Replying to mmetz:

Replying to metello:

The file was too large to attach. I uploaded here: ​http://psr-shared.s3.amazonaws.com/public/admin/2C66EC59/R_CONTOUR_BUG.zip

Coordinates of some points of discontinuity: (384073.870002,8827636.45371), (402242.43372,8799021.33681), (409632.732253,8796197.58953)

I can confirm the missing segments, the previous fix to prevent contours from tracing back on themselves was not working. Working on it...

r.contour has been fixed in master, relbr76, and relbr74.

[neteler]

Closing as fixed.

[martinl]

See, for a record, ​https://github.com/OSGeo/grass/pull/6