Is $S_1 \times S_1 \sqcup_{(x,y) \sim (x,x+y)} S_1 \times S_1$ homotopy equivalent to $S_1$?
I do not think it is. My motivation is in proving that the fiber of a map in a certain math overflow answer by a senior professor, who I don't want to name, is wrong.
Here I am letting the the torus be $[0,1]_A/\{0,1\} \times [0,1]_B/\{0,1\}$. This identification identifies the based homology class $A+B$ in the second copy of the torus with the homology class $A$ in the first copy of the torus.
Do you have any ideas of showing how this is not $S_1$?