Trouble saving screenshots with dots in names

[douglasrizzo]

If the resultant image file contains any dots in its name, the software gets confused with its format during saving, e.g.:

$ deepin-screenshot -s "~/Pictures/screenshots/my.photo.png"

And the relevant piece of the log:

2018-08-16, 16:00:25.001 [Debug  ] [   0] toolBar "~/Pictures/screenshots/my.photo.png"
2018-08-16, 16:00:25.001 [Warning] [   0] Invalid image format! Screenshot will quit, suffix: "photo.png"
2018-08-16, 16:00:25.001 [Debug  ] [   0] process savepath1: ""
2018-08-16, 16:00:25.002 [Debug  ] [   0] shotCurrentImg shotFullScreen
2018-08-16, 16:00:25.019 [Warning] [   0] QFSFileEngine::open: No file name specified
2018-08-16, 16:00:25.019 [Warning] [   0] QFile::remove: Empty or null file name